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PUPUK HIJAU Diabstraksikan oleh : Prof.Dr.Ir.Soemarno , M.S. Jurs tanah fpub maret 2012.
PUPUK HIJAU Diabstraksikanoleh: Prof.Dr.Ir.Soemarno, M.S. Jurstanahfpubmaret 2012 “Green manure, also called a cover crop, is a great way to add nutrients to the soil. Green manure means planting a crop that is meant to be incorporated into the soil to increase it's fertility. Green manures can be planted in the fall after the herbs have been harvested. You can also plant your green manures as part of your crop rotation during the growing season.” Sumber; http://herbgardens.about.com/od/fertilizer/a/greenmanure.htm
PUPUK ORGANIK Pupuk organik adalah pupuk yang tersusun dari materi /substansi organik, seperti hasil-hasil pelapukan sisa -sisa tanaman, hewan, dan manusia. Pupuk organik dapat berbentuk padat atau cair yang digunakan untuk memperbaiki sifat fisik, kimia, dan biologitanah. Pupuk organik mengandung banyak bahan organik daripada kadar haranya. Sumber bahan organik dapat berupa kompos, pupuk hijau, pupuk kandang, sisa panen (jerami, brangkasan, tongkol jagung, bagas tebu, dan sabut kelapa), limbah ternak, limbah industri yang menggunakan bahan pertanian, dan limbah kota (sampah). Sutanto, Rachman. (2002). Pertanian organik: Menuju Pertanian Alternatif dan Berkelanjutan. Jakarta:Kanisius. ISBN 979-21-0187-X,9789792101874 Suriadikarta, Didi Ardi., Simanungkalit, R.D.M. (2006).Pupuk Organik dan Pupuk Hayati. Jawa Barat:Balai Besar Penelitian dan Pengembangan Sumberdaya Lahan Pertanian. Hal 2. ISBN 978-979-9474-57-5. Sumber: http://id.wikipedia.org/wiki/Pupuk_organik ….. Diunduh 11/3/2012
PUPUK HIJAU Pupuk hijau adalah pupuk organik yang berasal dari tanaman atau sisa- sisa panen. Bahan tanaman ini dapat dibenamkan pada waktu masih hijau – segar atau setelah dikomposkan. Sumber pupuk hijau adalah sisa-sisa tanaman (sisa panen) atau tanaman yang ditanam secara khusus sebagai penghasil pupuk hijau, seperti sisa–sisa tanaman, kacang-kacangan, dan tanaman paku air(Azolla). Jenis tanaman yang dijadikan sumber pupuk hijau diutamakan dari jenis legume, karena tanaman ini mengandung nitrogen yang relatif tinggi, dibandingkan dengan jenis lainnya. Legume juga relatif mudah terdekomposisi sehingga penyediaan haranya menjadi lebih cepat. Pupuk hijau bermanfaat untuk meningkatkan kandungan bahan organik dan unsur hara di dalam tanah, sehingga terjadi perbaikan sifat fisika, kimia, dan biologi tanah, yang selanjutnya berdampak pada peningkatan produktivitas tanah dan ketahanan tanah terhadap erosi. Pupuk hijau digunakan dalam: Penggunaan tanaman pagar, yaitu dengan mengembangkan sistem pertanaman lorong, dimana tanaman pupuk hijau ditanam sebagai tanaman pagar berseling dengan tanaman utama. Penggunaan tanaman penutup tanah, yaitu dengan mengembangkan tanaman yang ditanam sendiri, pada saat tanah tidak ditanami tanaman utama atau tanaman yang ditanam bersamaan dengan tanaman pokok bila tanaman pokok berupa tanaman tahunan. Parnata, Ayub.S. (2004). Pupuk Organik Cair. Jakarta:PT Agromedia Pustaka. Hal 15-18. Sumber: http://id.wikipedia.org/wiki/Pupuk_organik ….. Diunduh 11/3/2012
KOMPOS Kompos merupakan sisa bahan organik yang berasal dari tanaman, hewan, dan limbah organik yang telah mengalami proses dekomposisi atau fermentasi. Jenis tanaman yang sering digunakan untuk kompos di antaranya jerami, sekam padi, tanaman pisang, gulma, sayuran yang busuk, sisa tanaman jagung, dan sabut kelapa. Bahan dari ternak yang sering digunakan untuk kompos di antaranya kotoran ternak, urine, pakan ternak yang terbuang, dan cairan biogas. Tanaman air yang sering digunakan untuk kompos di antaranya ganggang biru, gulma air, eceng gondok, dan azola. Beberapa manfaat kompos adalah: Memperbaiki struktur tanah. Memperkuat kemantapan agregat pada tanah berpasir. Meningkatkan daya simpan dan daya serap air. Memperbaiki drainase dan pori – pori tanah. Menambah ketersediaan unsur hara. Kompos diaplikasikan dengan cara menyebarkannya di sekeliling tanaman. Kompos yang layak digunakan adalah yang sudah matang, ditandai dengan menurunnya temperatur kompos (di bawah 400 c). Djuarni, Nan, Kristian, Setiawan, Budi Susilo.(2006). Cara Cepat Membuat Kompos. Jakarta:AgroMedia.Hal 36-38. Sumber: http://id.wikipedia.org/wiki/Pupuk_organik ….. Diunduh 11/3/2012
Tanaman Orok-orok (Crotalaria juncea) cocok sebagai pupuk hijau Tanaman Crotalaria juncea di samping hasil biomasanya tinggi juga mempunyai kandungan N tinggi pula (3,01 % N). Tanaman ini cukup lunak sehingga cocok digunakan utuk sebagai pupuk hijau. Pada waktu yang lalu tanaman selalu ditanam setelah panen selesai. Sebenarnya penggunaan pupuk hijau ini bukan barang baru lagi, namun karena sudah banyak ditinggalkan oleh petani maka pupuk hijau ini terabaikan. Misalnya pada tahun tujuh puluhan, merupakan suatu keharusan pihak pabrik tembakau di Klaten, menanam Crotalaria juncea (orok-orok) pada setiap habis panen tembakau, bertujuan untuk mengembalikan dan memperbaiki kesuburan tanahnya. Setelah tembakau dipanen, ditanam orok-orok, setelah besar maka tanaman orok-orok ini dirobohkan dan dicampur dengan tanah saat pengolahan tanah (pembajakan) yang kemudian digenangi. Pada saat ini keharusan tersebut sukar dipenuhi baik oleh pihak penguysaha maupun petani. Petani merasa keberatan bila sawahnya ditanami legum (orok-orok), karena dianggap tidak produktif, selama penanaman orok-orok (sekitar 1 bulan). Sumber: http://lestarimandiri.org/id/pupuk-organik/pupuk-hijau.html ….. Diunduh 10/3/2012
TANAMAN PUPUK HIJAU Pupuk hijau adalah pupuk organik yang berasal dari tanaman atau berupa sisa panen. Bahan tanaman ini dapat dibenamkan pada waktu masih hijau atau setelah dikomposkan. Manfaat pupuk hijau : Meningkatkan kandungan bahan organik dan unsur hara di dalam tanah sehingga terjadi perbaikan sifat fisika, kimia, dan biologi tanah, yang selanjutnya berdampak pada peningkatan produktivitas tanah dan ketahanan tanah terhadap erosi. Sumber pupuk hijau : Sumber pupuk hijau dapat berupa sisa-sisa tanaman (sisa panen) atau tanaman yang ditanam secara khusus sebagai penghasil pupuk hijau atau berasal dari tanaman liar. Jenis tanaman yang dijadikan sumber pupuk hijau diutamakan dari jenis legume, karena tanaman ini mengandung hara yang relatif tinggi(terutama N) dibandingkan dengan jenis tanaman lainnya, tanaman legume juga relatif mudah terdekomposisi sehingga penyediaan haranya menjadi lebih cepat. Sumber: http://lestarimandiri.org/id/pupuk-organik/pupuk-hijau.html ….. Diunduh 10/3/2012
PUPUK HIJAU: Sisa tanaman Sisa tanaman (sisa panen) merupakan sumber BO yang paling ekonomis karena bahan ini merupakan hasil sampingan dari kegiatan usaha tani, sehingga tidak membutuhkan biaya untuk pengadaannya. Sisa tanaman walaupun kandungan haranya relatif rendah, namun karena total sisa tanaman yang dihasilkan setiap musim panen banyak, maka total unsur hara yang disumbangkan dari setiap musim panen tidak kalah dibandingkan jenis legume. Total hara yang terkandung dalam sisa panen (kecuali akar) Sumber: “Pupuk Organik dan Pupuk Hayati” by Litbang, Bogor http://lestarimandiri.org/id/pupuk-organik/pupuk-hijau/273-tanaman-pupuk-hijau.html….. Diunduh 10/3/2012
TANAMAN PAGAR Salahsatucaramenyediakansumberpupukhijauadalahdenganmengembangkansistempertanamanlorong, dimanatanamanpupukhijauditanamsebagaitanamanpagarberselingdengantanamanutama. Tanamanpagardapatmenghasilkanbiomasasecaraperiodik; padausimhujantanamandapatdipangkassetiap 2 bulan. Aplikasisistempertanamanlorongpadalahan miring, dimana legume ditanamsearahkontursangatefektifuntukmenekanerosi. Secaraumumsetiap legume dapatdigunakansebagaitanamanpagar, namunlebihefektifbilatanamanpagarmemenuhisifat-sifatsebagaiberikut : Berakardalam agar tidakmenjadipesaingbagitanamansemusim Pertumbuhancepatdansetelahpemangkasancepatbertunaskembali Mampumenghasilkanbahanhijauandalamjumlahbanyakdanterusmenerus yang dapatdigunakansebagaipupukhijau Mampumemperbaikikandungan N dalamtanahdankandunganharalainnya. Sumber: “Pupuk Organik dan Pupuk Hayati” by Litbang, Bogor http://lestarimandiri.org/id/pupuk-organik/pupuk-hijau/273-tanaman-pupuk-hijau.html….. Diunduh 10/3/2012
Tanaman legume yang dapat digunakan sebagai tanaman pagar : Produksi pangkasan (data pangkasan tahun kedua dan ketiga) beberapa jenis tanaman pagar Sumber: “Pupuk Organik dan Pupuk Hayati” by Litbang, Bogor http://lestarimandiri.org/id/pupuk-organik/pupuk-hijau/273-tanaman-pupuk-hijau.html….. Diunduh 10/3/2012
TANAMAN PENUTUP TANAH Tanamanpenutuptanahadalahtanaman yang ditanamsendiriyaknipadasaattanahtidakditanamitanamanutamaatautanaman yang ditanambersamaandengantanamanpokokbilatanamanpokokberupatanamantahunan. Tujuanpenanamantanamanpenutuptanah : Melindungitanahdaridayaperusakbutir-butirhujan Mempertahankan/memperbaikikesuburantanah Menyediakan BO Merupakantindakanrehabilitasilahan yang murahdanmudahdiaplikasikan Cover crops are crops planted primarily to manage soil fertility, soil quality, water, weeds, pests, diseases, biodiversity and wildlife in agroecosystems (Lu et al. 2000), ecological systems managed and largely shaped by humans across a range of intensities to produce food, feed, or fiber. Cover crops are of interest in sustainable agriculture as many of them improve the sustainability of agroecosystem attributes and may also indirectly improve qualities of neighboring natural ecosystems. Farmers choose to grow and manage specific cover crop types based on their own needs and goals, influenced by the biological, environmental, social, cultural, and economic factors of the food system within which farmers operate. Lu, Y. C., K. B. Watkins, J. R. Teasdale, and A. A. Abdul-Baki. 2000. Cover crops in sustainable food production. Food Reviews International 16:121-157. Sumber: “Pupuk Organik dan Pupuk Hayati” by Litbang, Bogor http://lestarimandiri.org/id/pupuk-organik/pupuk-hijau/273-tanaman-pupuk-hijau.html….. Diunduh 10/3/2012
AZOLLA Azolla merupakan salah satu sumber N alternatif khususnya untuk padi sawah. Azolla merupakan paku air ukuran mini yang bersimbiosis dengan Cyanobacteria pemfiksasi N2. Azolla merupakan satu-satunya genus dari paku air mengapung sukuAzollaceae. Terdapat tujuh spesies yang termasuk dalam genus ini. Azolla dikenal mampu bersimbiosis dengan bakteri biru-hijauAnabaena azollae dan mengikat nitrogen langsung dari udara. Potensi ini membuat Azolla digunakan sebagai pupuk hijau baik di lahan sawah maupun lahan kering. Pada kondisi optimal Azolla akan tumbuh baik dengan laju pertumbuhan 35% tiap hari Nilai nutrisi Azolla mengandung kadar protein tinggi antara 24-30%. Kandungan asam amino essensialnya, terutama lisin 0,42% lebih tinggi dibandingkan dengan konsentrat jagung, dedak, dan beras pecah (Arifin, 1996) dalam Akrimin 2002. Tanaman Azolla Sp. memang sudah tidak diragukan lagi konstribusinya dalam memengaruhi peningkatan tanaman padi. Hal ini telah dibuktikan dibeberpa tempat dan beberapa negara. Konstribusi terbesar azolla adalah dengan menjaga hasil panen tetap tinggi. Meskipun penggunaannya sebagai pupuk hijau pada tanaman padi masih dilakukan di China dan Vietnam, dengan adanya peningkatan biaya tenaga kerja, membuatnya kurang diminati. Sejalan dengan perkembangan pupuk hijau, penggunaan azolla lebih banyak dimanfaatkan untuk budidaya perikanan. Dengan adanya mindazbesi yang menggabungkan mina padi dengan azolla, selain menjadikannya sebagai pakan perikanan juga konstribusi dapat digunakan untuk peningkatan produksi padi. Sumber: “Pupuk Organik dan Pupuk Hayati” by Litbang, Bogor http://lestarimandiri.org/id/pupuk-organik/pupuk-hijau/273-tanaman-pupuk-hijau.html….. Diunduh 10/3/2012
Terdapat tujuh jenis Azolla: Asia Azolla japonica Franch. & Sav. dari Jepang A. filiculoidesLam. A. pinnataR. Br. dari Asia Tenggara, juga dari Afrika Afrika A. nilotica Dcne. ex Mett. Amerika A. caroliniana Willd., dari Amerika Utara A. mexicana Presl., dari Meksiko A. microphylla Kaulf. Rice-duck-azolla system developed by a Japanese farmer http://www.asahi-net.or.jp/~it6i-wtnb/azollaE.html Sumber: http://id.wikipedia.org/wiki/Azolla….. Diunduh 11/3/2012
Sesbania rostrata Sesbania rostrata merupakan tanaman legume yang potensial sebagai sumber N pada lahan sawah. Tanaman ini dapat tumbuh pada keadaan tergenang, dan dapat membentuk bintil tidak hanya pada akar tetapi juga pada batang. Oleh karena itu tanaman ini mempunyai kemampuan menambat N yang relatif tinggi. Sesbania is a genus of flowering plants in the pea family, Fabaceae and the only genus found in Tribe Sesbanieae. Notable species include the Rattlebox (Sesbania drummondii), Spiny Sesbania (Sesbania bispinosa), and Sesbania sesban, which is used in cooking. Plants of this genus, some of which are aquatic, can be used in alley cropping to increase the soil's nitrogen content. The species of Rhizobia responsible for Nitrogen fixation in Sesbania rostrata is Azorhizobium caulinodans. http://en.wikipedia.org/wiki/Sesbania Sumber: “Pupuk Organik dan Pupuk Hayati” by Litbang, Bogor http://lestarimandiri.org/id/pupuk-organik/pupuk-hijau/273-tanaman-pupuk-hijau.html….. Diunduh 10/3/2012
Sesbania grandiflora (L.) Poir. Sesbania grandiflora is a loosely branching tree up to 15 m tall. Its leaves are pinnately compound up to 30 cm long with 20-50 leaflets in pairs, dimensions 12-44 x 5-15 mm, oblong to elliptical in shape. Flowers are large, white, yellowish, rose pink or red with a calyx 15-22 mm long. The standard has dimensions up to 10.5 x 6 cm. Pods are long (20-60 cm) and thin (6-9 mm) with broad sutures containing 15-50 seeds. It is well adapted to hot, humid environments and does not grow well in the subtropics particularly in areas with cool season minimum temperatures below about 10°C. It is outstanding in its ability to tolerate waterlogging and is ideally suited to seasonally waterlogged or flooded environments. When flooded, they initiate floating adventitious roots and protect their stems, roots and nodules with spongy, aerenchyma tissue. Evans and Macklin (1990) report that S. grandiflora is adapted to rainfall conditions of 2,000-4,000 mm but will grow in areas receiving only 800 mm. In northern Thailand, S. grandiflora was an excellent supplement to dairy cows fed predominantly grass hay. Most reports indicate that the crude protein content of S. grandiflora foliage is generally greater than 20% and often above 25%. Dry matter digestibility of Sesbania species is superior to that of most other tree and shrub legumes. In northeast Thailand, Akkasaeng et al. (1989) found that the in vitro dry matter digestibility of S. grandiflora, S. sesban and S. sesban var. nubica was 66, 75 and 66% respectively, all higher than that of 15 other tree legumes that were tested. van Eys et al. (1986) reported that S. grandiflora contained more crude protein but less fibre than Gliricidia sepium and Leucaena leucocephala while their in vitro dry matter digestibilities were 73.3, 65.2 and 62.2% respectively. Sumber: http://www.fao.org/ag/AGP/AGPC/doc/Gbase/data/pf000171.htm ….. Diunduh 11/3/2012
PUPUK HIJAU (MAPORINA.COM -- Written by beta Monday, 09 August 2004. Last Updated ( Wednesday, 02 September 2009 ) Pupukhijaumerupakanpupuk yang bahannyaberasaldaritanamanataukomponentanaman yang dibenamkankedalamtanah. Jenistanaman yang banyakdigunakandanmemanglebihbaikkualitasnyadibandingtanaman lain adalahjenis/familiaLeguminoceae. Jenistanamantersebutmengandungunsurhara yang lehihbaik, terutamaunsur Nitrogen dibandingtanaman lain. Jenistanamanleguminosamempunyaidayaseraphara yang lebihbesardanmempunyaibintilakar. Di dalammetabolismenyabersimbiosisdenganbakteri Rhizobium yang dapatmengikatunsur nitrogen dariudara. Keuntungan yang didapatjikamenggunakanpupukhijau : Mampumemperbaikistrukturdanteksturtanahsertainfiltrasi air. Mencegahadanyaerosi Sangatbermanfaatpadadaerah-daerah yang sulitdijangkauuntuksuplaipupukanorganik. Manfaat lain spesiespupukhijaudapatdijadikansebagaipakanternak, kayubakarbahkansebagaimakananmanusia. Syarat-syarattanamanpupukhijau yang akandipilihadalahsebagaiberikut : Menghasilkanbanyakbiomas. Dapatmenekandanmengendalikangulma. Prosentaseproduksidaunlebihbesardaripadabagian yang berkayu. Mempunyaikemampuankemampuanmengikatnitrogennyatinggidanmelepaskannutrisipadatanah. Berumurpendek, cepattumbuh, mempunyaikemampuanmegakumulasihara. Sumber: ….. Diunduh 10/3/2012. http://maporina.com/index.php?option=com_content&task=view&id=2&Itemid=1
PUPUK HIJAU (MAPORINA.COM -- Written by beta Monday, 09 August 2004. Last Updated ( Wednesday, 02 September 2009 ) Tanaman yang berfungsi sebagai pupuk hijau, selain tanaman kacang-kacangan/polong-polongan, jenis rumput-rumputan ( rumput gajah ), dan Azolla juga baik sebagai bahan pupuk hijau. Tanaman pupuk hijau yang cocok ditanam pada lahan pematang tanaman padi maupun lahan-lahan yang kosong, sedangkan Azolla adalah merupakan jenis tanaman pakuan air yang hidup di perairan. Seperti halnya tanaman leguminosae, Azolla mampu menambat N2 udara karena berasosiasi dengan sianobakteri (Anabaena azollae) yang hidup di dalam rongga daun Azolla. Menurut Khan (1983), kemampuan Azolla mengikat N2 dari udara berkisar antara 400 – 500 kg N/ha/tahun. Azolla berkembang Sangat cepat dan dapat menghasilkan biomassa sebanyak 10-15 ton/ha dengan C/N ratio 12 – 18, sehingga dalam waktu satu minggu Azolla telah terdekomposisi dengan sempurna. Sumber: ….. Diunduh 10/3/2012. http://maporina.com/index.php?option=com_content&task=view&id=2&Itemid=1
KEUNTUNGAN PUPUK HIJAU Green manuring can bring a number of advantages to the grower: Adding organic matter to the soil Increasing biological activity Improving soil structure Reduction of erosion Increasing the supply of nutrients available to plants (particularly by adding nitrogen to the system by fixation) Reducing leaching losses Suppressing weeds Reducing pest and disease problems Providing supplementary animal forage Drying and warming the soil Green manure crops are also useful for weed control, erosion prevention, and reduction of insect pests and diseases. The deep rooting properties of many green manure crops make them efficient at suppressing weeds. Green manure crops often provide habitat for many native pollinators as well as predatory beneficial insects, which allow for a reduction in the input of insecticides where cover crops are planted. Some green manures are also successful at suppressing plant diseases, especially Verticillium wilt in potato. Incorporation of green manures into a farming system can drastically reduce, if not eliminate, the need for additional products such as supplemental fertilizers and pesticides. Vasilakoglou, Ioannis, Dhima, Kico, Anastassopoulos, Elias, Lithourgidis, Anastasios, Gougoulias, Nikolaos, and Chouliaras, Nikolaos. 2011. Oregano green manure for weed suppression in sustainable cotton and corn fields. Weed Biology and Management 11:38-48. Larkin, Robert P., Honeycutt, Wayne, and Olanya Modesto, O. 2011. Management of Verticillium Wilt of Potato with Disease-Suppressive Green Manures and as Affected by Previous Cropping History. Plant Dis. 95:568-576. Sumber: www.organicadvice.org.uk/.../green_manures....….. Diunduh 10/3/2012
KERUGIAN PUPUK HIJAU A number of disadvantages can also be identified: Direct costs of seed and extra cultivations Lost opportunities for cash cropping Extra work at busy times of the year Exacerbated pest and disease problems (due to the ‘green bridge’ effect) Potential for the green manures to become weeds in their own right A wide range of plant species can be used as green manures. Different ones bring different benefits and the final choice is influenced by many considerations which will be examined later on in this review. If the most is to be made from green manure crops it is important that they are carefully integrated into the crop rotation and proper attention paid to their husbandry. Green manure crops Another important contribution of green manure to an agricultural field is the nitrogen fixing ability and consequent nitrogen accumulation in the soil, particularly of those leguminous crops used. Depending on the species of cover crop grown, the amount of nitrogen released into the soil lies between 40 and 200 pounds per acre. With green manure use, the amount of nitrogen that is available to the succeeding crop is usually in the range of 40-60% of the total amount of nitrogen that is contained within the green manure crop. Sullivan, Preston. 2003. Overview of Cover Crops and Green Manures: Fundamentals of Sustainable Agriculture. www.attrat.ncat.org. Sumber: www.organicadvice.org.uk/.../green_manures....….. Diunduh 10/3/2012
THE EFFECTS OF GREEN MANURES Minimising nitrate leaching Large quantities of nitrate can be lost from soil which is left bare overwinter. This is because, unlike other nutrient ions, nitrate is not strongly attracted to soil particles. Any that is in solution in the autumn will be washed away as water moves down through the soil with the onset of heavy winter rains. This is bad for the environment (nitrate can contribute to the formation of algal blooms in watercourses) and for human health (when contaminated water is drunk). As a result EU regulations have been introduced to control farming practices likely to result in large nitrate losses. This has resulted in the establishment of Nitrate Sensitive Areas (Tunney, 1992). For farmers, leaching also represents the loss of a valuable resource – this is particularly serious for organic farmers because it is much harder for them to replace the lost nitrogen. It is widely recognised that one of the best ways of preventing nitrate leaching is to maintain a vigorously growing crop over the winter period (MAFF, 1998). Tunney, H (1992). The EC Nitrate Directive. Aspects of Applied Biology 30: 5-10. MAFF (1998). Code of Good Agricultural Practice for the Protection of Water (Available form DEFRA). Sumber: www.organicadvice.org.uk/.../green_manures....….. Diunduh 10/3/2012
An example of overwinter nitrate concentrations below bare soil plots and plots on which grazing rye was growing. This trial was set up directly after the incorporation of a grass/clover ley. Winter green manures can be very effective crops for ‘mopping up’ excess nitrate in the soil in the autumn and this effect was studied at HDRA. One example is shown in figure , nitrate concentrations were measured at 60cm depth and the wave of nitrate passing down the profile can be clearly seen. GREEN MANURES. A review conducted by HDRA as part of HDC Project FV 299: An investigation into the adoption of green manures in both organic and conventional rotations to aid nitrogen management and maintain soil structure. Project Leader: Peter Knight Vegetable Consultancy Services Ltd. The Finches, Cake Street Old Buckenham . Attleborough, Norfolk NR17 1RU
KETERSEDIAAN N BAGI TANAMAN BERIKUTNYA Of all the nutrient elements, nitrogen is the most labile in soil and the one most likely to be affected by green manures. This is because it exists in so many different forms that are inter-converted by a range of biological processes – some of these forms are prone to losses (by leaching or gaseous emissions of ammonia, nitrogen or nitrous oxides). For some crops (eg cauliflowers) it is particularly important that sufficient nitrogen is available at certain growth stages to ensure that the plants produce yields of a marketable quality and correct management of green manures can be used to manipulate its availability. Large amounts of nitrogen are added to the soil by a successful green manure (eg an overwintered crop of vetch may accumulate up to 200kg N/ha by early May). How soon this becomes available to plants (a process of conversion of complex molecules to ammonium and nitrate ions known as mineralisation) will depend on many factors (Jarvis et al , 1996). Jarvis, SC, Stockdale, EA, Shepherd MA & Powlson DS (1996). Nitrogen mineralization in temperate agricultural soils; processes and measurements. Advances in Agronomy 57: 187-235.
MINERALISASI PUPUK HIJAU Mineralisation proceeds fastest when the soil is warm and moist. The quantity of nitrogen released is also dependant on the total amount actually added to the soil and the chemical composition of the incorporated material. It is not just the C;N ratio which is important. The carbon can be in different forms (eg lignin is more resistant to decomposition than cellulose) and some plants contain chemicals (eg polyphenols) which can inhibit microbial action. Rahn et al (1999) compared the chemical characteristics of various agricultural residues with their patterns of decomposition. Incorporation of cover crops into the soil is immediately followed by an increase in abundance of soil microorganisms that aid in the decomposition of this fresh material. The degradation of plant material allows the nutrients held within the green manure to be released and made available to the succeeding crop. This additional decomposition also allows for the re-incorporation of nutrients that are found in the soil on a particular farm such as nitrogen (N), potassium (K), phosphorus (P), calcium (Ca), magnesium (Mg), and sulfur (S). Microbial activity in the soil also leads to the formation of mycelium and viscous materials which benefit the health of the soil by increasing its soil structure (i.e. by aggregation). Soil that is well- aggregated has increased aeration and water infiltration rates, and is more easily turned or tilled than non- aggregated soil. Further aeration of the soil results from the ability of the root systems of many green manure crops to efficiently penetrate compact soils. The amount of humus found in the soil also increases with higher rates of decomposition, which is beneficial for the growth of the crop succeeding the green manure crop. Rahn, C.R., Bending, G., Lillywhite, R., Turner M. (1999). Chemical characterisation of vegetable and arable crop residue materials: a comparison of methods.. Journal of the Science of Food and Agriculture 79 p1715-1721
PUPUK HIJAU – KESUBURAN TANAH Results from an experiment where overwintered vetch was incorporated at three different dates in the spring. Vetch is a plant which has a high nitrogen content throughout its life (3-4% of its dry weight). And is consequently readily mineralisable. It puts on a lot of growth in late April and the highest levels of mineral nitrogen resulted from the latest incorporation date in May. In some cases a ‘priming effect’ may be seen ie the addition of green manures can stimulate the mineralisation of organic matter already in the soil. See Rayns and Lennartsson (1995) for more information. An example of patterns of soil mineral nitrogen (0-30cm) after incorporation of an overwintered vetch crop at three different dates in the spring Rayns, FW & Lennartsson, M (1995) The nitrogen dynamics of winter green manures. In HF Cook and HC Lee (eds) Soil Management in Sustainable Agriculture, Proceedings 3rd International Conference on Sustainable Agriculture, Wye College 1993. Wye College Press, Ashford, pp 308-311.Sumber: ….. Diunduh 10/3/2012
PUPUK HIJAU – KETERSEDIAAN HARA The most extensive study was carried out by Jensen et al. (2005) where the effectiveness of five types of catch crop (Italian ryegrass, lupin, chicory, rumex and kidney vetch) were compared on a soil deficient in P and K. In this study, nutrient uptakes of catch crops were all low with 2-4 kg P / ha and 15-30kg K /ha taken up annually. This low uptake was attributed to low biomass production (1-2 t/ha) of the catch crops on the infertile soils. Moreover, after incorporation, the catch crops had no effect on the P uptake in the subsequent barley crop. The conclusions that could be drawn from this study were that under these conditions of poor soil fertility, catch crops made very little contribution to making P and K more available to subsequent crops. However, this work does not answer the question as to whether they have a role to prevent losses on more fertile soils. The root systems of some varieties of green manure grow deep in the soil and bring up nutrient resources unavailable to shallower-rooted crops. Jensen, L., Pedersen, A., Magid. J. & Nielsen, N. (2005) Catch crops have little effect on P and K availability of depleted soils. Newsletter from Danish Research Centre for Organic Farming • June 2005 • No. 2.
PUPUK HIJAU – KETERSEDIAAN FOSFAT There is work that has focussed on the ability of some plants, particularly lupins and buckwheat to increase phosphate mobility in the soil. Lupins grown in P deficient soil were found to extrude protons and organic acids such as citric acid, increasing the mobility and uptake of P (Shen et al., 2005; Neuman et al., 2000). P deficiency also stimulated the formation of cluster roots which are more active in P uptake (Sas et al., 2001). Buckwheat has also been shown to extrude organic acids and under conditions of low P availability on a calcareous soil, P uptake was ten fold higher than in wheat (Zhu et al., 2002). Phosphorus uptake by green manure crops in 2004 http://www.organicagcentre.ca/Docs/OACC_bulletins06/OACC_Bulletin17_phos_avail.pdf Sas, L., Rengel, Z. & Tang, C. (2001) Excess cation uptake, and extrusion of protons and organic acid anions by Lupinus albus under phosphorus deficiency Plant Science 160: 1191-1198 Shen, J. Li, H., Neumann, G. & Zhang, F. (2005) Excess cation uptake, and extrusion of protons and organic acid anions by Lupinus albus under phosphorus deficiency. Plant Science 168:837-845. Zhu, Y,G., He, Y,Q, Smith, S.E. & Smith, F.A. (2002) Buckwheat (Fagopyrum esculentum Moench) has high capacity to take up phosphorus (P) from a calcium (Ca)-bound source. Plant and Soil 239: 1–8.
PUPUK HUJAI – UNSUR HARA LAIN There is also work to suggest that micronutrients such as sulphur may be leached out of sandy soils and eventually become deficient in low input systems (Eriksen & Askegaard, 2000). One study (Eriksen & Thorup- Kristensen, 2002) found that cruciferous crops such as winter rape or fodder radish were particularly effective at preventing sulphur being leached into lower soil profiles. Moreover this increased availability was realised as an increase in sulphur content in the subsequent barley crop. Other green manures such as chicory have also been reported to accumulate large amounts of micronutrients including sulphur, boron, manganese, molybdenum, and zinc (Rumball, 1986). Sulfur mineralization in two soils amended with organic manures, crop residues, and green manures Kotha Sammi Reddy, Muneshwar Singh, Anand Swarup, Annangi Subba Rao, Kamlesh Narain Singh. Journal of Plant Nutrition and Soil Science. Vol 165, Issue 2, p. 167–171, April 2002. The mineralization of sulfur (S) was investigated in a Vertisol and an Inceptisol amended with organic manures, green manures, and crop residues. Field-moist soils amended with 10 g kg—1 of organic materials were mixed with glass beads, placed in pyrex leaching tubes, leached with 0.01 M CaCl2 to remove the mineral S and incubated at 30 °C. The leachates were collected every fortnight for 16 weeks and analyzed for SO4-S. The amount of S mineralized in control and in manure-amended soils was highest in the first week and decreased steadily thereafter. The total S mineralized in amended soils varied considerably depending on the type of organic materials incorporated and soil used. The cumulative amounts of S mineralized in amended soils ranged from 6.98 mg S (kg soil)—1 in Inceptisol amended with wheat straw to 34.38 mg S (kg soil)—1 in Vertisol amended with farmyard manure (FYM). Expressed as a percentage of the S added to soils, the S mineralized was higher in FYM treated soils (63.5 to 67.3 %) as compared to poultry manure amended soils (60.5 to 62.3 %). Similarly the percentage of S mineralization from subabul (Leucaena leucocephala) loppings was higher (53.6 to 55.5 %) than that from gliricidia (Gliricidia sepium) loppings (50.3 to 51.1 %). Regression analysis clearly indicated the dependence of S mineralization on the C : S ratio of the organic materials added to soil. The addition of organic amendments resulted in net immobilization of S when the C : S ratio was above 290:1 in Vertisol and 349:1 in Inceptisol. The mineralizable S pool (So) and first-order rate constant (k) varied considerably among the different types of organic materials added and soil. The So values of FYM treated soils were higher than in subabul, gliricidia, and poultry manure treated soils. Eriksen, J & Askegaard, M (2000) Sulphate leaching in an organic crop rotation on sandy soil in Denmark. Agriculture, Ecosystems and Environment 78:107-114. Rumball, W. (1986) ‘Grasslands Puna’ chicory (Cicorium intybusL.) New Zealand Journal of Experimental Agriculture 14:105-107
PUPUK HIJAU – AGREGASI TANAH Green manures can improve soil structure in a number of ways. The extensive fine roots of some, such as rye, enmesh the soil, helping to stabilise aggregates and increasing pore size thus improving seedbed structure (Breland, 1995). Some species also produce deep tap roots which help break up compacted soil. A series of pot experiments (Lofkvist et al., 2005) identified lucerne roots as being particularly effective at penetrating hard layers, with chicory, lupin, red clover as having intermediate ability and barley the poorest. A key function of green manures is the addition of organic matter to the soil. They do this whilst still growing, producing root exudates which provide food for micro organisms, which in turn produce polysaccharide gums, which “glue” soil aggregates together (Reid & Goss, 1981). They may also provide a bridge between mycorrhizal crops in order to maintain a high population of soil mycorrhiza, which help maintain soil structure, again by enmeshing soil aggregates. Brassicas and lupins, however, are non mycorrhizal and will break that bridge. Breland, T. (1995) Green manuring with clover and ryegrass catch crops undersown in spring wheat : effects on soil structure Soil Use and Management 11:163-167. Löfkist, J., Whalley, W.R. & Clark, L.J. (2005) A rapid screening method for good root-penetration ability: Comparison of species with very different root morphology Acta Agriculturae Scandinavica 55:120-124. Reid, J.B. & Goss, M.J. (1981) Effect of living roots of different plant species on the aggregate stability of two arable soils European Journal of Soil Science 32:521.
PUPUK HIJAU - BOT Once incorporated, the green manure provides a pool of fresh organic matter and there are numerous examples where using green manures increases soil organic matter in comparison to treatments where inorganic fertilisers alone are applied (e.g. Shepherd et al., 2002). This organic matter provides food to soil micro organisms, encouraging an increase in numbers and activity (N’Dayegamuye & Tran, 2001). Managing Crop Residue with Green Manure, Urea, and Tillage in a Rice–Wheat Rotation Milkha S. Aulakh, T. S. Khera, John W. Doran, and Kevin F. Bronson. Soil Sci. Soc. Am. J. 65:820–827 (2001). Shepherd, M.A., Harrison, R. & Webb, J.(2002) Managing soil organic matter – implications for soil structure on organic farms. Soil Use and Management 18:284 N’Dayegamiye, A & Tran, T.S. (2001) Effects of green manures on soil organic matter and wheat yields and N nutrition Canadian Journal of Soil Science. 81: 371–382
PUPUK HIJAU - EROSI TANAH The more succulent a green manure is the more rapidly it will decay once incorporated and the less effect it will have on long term soil organic matter. Older woody green manures with a higher C:N ratio break down more slowly and breakdown is reported to decrease to a very slow rate at C:N ratios above 16:1 (Enwezor, 1975). Legumes which have a low C:N ratio, break down rapidly so have little effect on long term soil organic matter but give a larger short term boost to soil structure as they have a large short term effect on soil micro organisms. Green manures can also play a part in reducing soil erosion both by wind and rain (Cransberg & McFarlane, 1994). Wind erosion is reduced as the green manure increases surface roughness reducing the wind speed close to the soil. The root system also has a binding effect on the soil. The green manure also reduces run off substantially, at ground covers of greater than 75%, reducing erosion by rain. Enwezor, W.O. (1976) The mineralization of nitrogen and phosphorus in organic materials of varying C:N and C:P ratios Plant and Soil 44:237-240 Cransberg, L. & McFarlane, D.J. (1994) Can perennial pastures provide the basis for a sustainable farming system in southern Australia? New Zealand Journal of Agricultural Research 37: 287-294
PUPUK HIJAU - PENGENDALIAN GULMA One of the major benefits of green manures is the ability to suppress weeds. This can occur by a number of different mechanisms that were reviewed by Liebman & Davis (2000). The various mechanisms are considered here. Firstly green manures can reduce weed infestation by disrupting cycles. Weeds often become adapted to a particular niche cycle of planting and cultivations if similar types of crops are grown continuously (Blackshaw, 1994). Growing a green manure adds diversity to the rotation and reduces the opportunities for weeds to become adapted to a niche cropping cycle. Competition for light, water and nutrients is another important way in which green manures reduce weed infestation. Rapidly growing crops with large ground cover, such as mustard, are the most effective at doing this and McLenaghen et al (1996) found that weed suppression was directly correlated with the ground cover of the green manure. Management practices associated with growing a green manure can also suppress weeds. The lack of soil disturbance during the long growing period of a ley can also reduce seed germination (Roberts & Feast, 1973). Blackshaw, R.E. (1994) Rotation affects downy brome (Bromus tectorum) in winter wheat (Triticum aestivum). Weed Technology 8:728-732 Mclenaghen, R.D., Cameron, K.C., Lampkin, N.H., Daly, M.L. & Deo, B. (1996) Nitrate leaching from ploughed pasture and the effectiveness of winter catch crops in reducing leaching losses. New Zealand Journal of Agricultural Research 39:413-420. Roberts, H.A. & Feast P.M.(1973) Emergence and longevity of seeds of annual weeds in cultivated and undisturbed soil. Journal of Applied Ecology 10:133-143.
GREEN MANURE = PUPUK HIJAU. In agriculture, a green manure is a type of cover crop grown primarily to add nutrients and organic matter to the soil. Typically, a green manure crop is grown for a specific period of time , and then ploughed under and incorporated into the soil while green or shortly after flowering. Green manure crops are commonly associated with organic agriculture, and are considered essential for annual cropping systems that wish to be sustainable. Traditionally, the practice of green manuring can be traced back to the fallow cycle of crop rotation, which was used to allow soils to recover. Sumber: http://en.wikipedia.org/wiki/Green_manure ..….. Diunduh 4/3/2012 Pupuk hijau adalah pupuk organik yang berasal dari tanaman atau berupa sisa panen. Bahan tanaman ini dapat dibenamkan pada waktu masih hijau atau setelah dikomposkan. Sumber: http://www.lestarimandiri.org/id/pupuk-organik/pupuk-hijau/273-tanaman-pupuk-hijau.html ..….. Diunduh 4/3/2012
FUNGSI PUPUK HIJAU Green manure crops may include legumes such as cowpeas, soybeans, annual sweet clover, vetch, sesbania, and velvet beans, as well as non-leguminous crops such as sudangrass, millet, sorghum, and buckwheat (Sullivan, Preston. 2003. Overview of Cover Crops and Green Manures: Fundamentals of Sustainable Agriculture. www.attrat.ncat.org.). Legumes are often used as green manure crops for their nitrogen fixing abilities, while non-leguminous crops are used primarily for weed suppression and addition of biomass to the soil. Pupukhijaubiasanyamempunyai multi-fungsi, termasukperbaikankualitastanahdanperlindungantanah: Leguminous green manures such as clover and vetch contain nitrogen-fixing symbiotic bacteria in root nodules that fix atmospheric nitrogen in a form that plants can use. Green manures increase the percentage of organic matter (biomass) in the soil, thereby improving water retention, aeration, and other soil characteristics. The root systems of some varieties of green manure grow deep in the soil and bring up nutrient resources unavailable to shallower-rooted crops. Common cover crop functions of weed suppression and prevention of soil erosion and compaction are often also taken into account when selecting and using green manures. Some green manure crops, when allowed to flower, provide forage for pollinating insects. Sumber: http://en.wikipedia.org/wiki/Green_manure ….. Diunduh 4/3/2012
MANFAAT PUPUK HIJAU Green manure crops are also useful for weed control, erosion prevention, and reduction of insect pests and diseases. The deep rooting properties of many green manure crops make them efficient at suppressing weeds (Vasilakoglou, Ioannis, Dhima, Kico, Anastassopoulos, Elias, Lithourgidis, Anastasios, Gougoulias, Nikolaos, and Chouliaras, Nikolaos. 2011. Oregano green manure for weed suppression in sustainable cotton and corn fields. Weed Biology and Management 11:38-48.). Green manure crops often provide habitat for many native pollinators as well as predatory beneficial insects, which allow for a reduction in the input of insecticides where cover crops are planted. Some green manures are also successful at suppressing plant diseases, especially Verticillium wilt in potato (Larkin, Robert P., Honeycutt, Wayne, and Olanya Modesto, O. 2011. Management of Verticillium Wilt of Potato with Disease-Suppressive Green Manures and as Affected by Previous Cropping History. Plant Dis. 95:568-576). Incorporation of green manures into a farming system can drastically reduce, if not eliminate, the need for additional products such as supplemental fertilizers and pesticides. Sumber: http://en.wikipedia.org/wiki/Green_manure ….. Diunduh 4/3/2012
COVER CROP = TANAMAN PENUTUP TANAH Cover crops are crops planted primarily to manage soil fertility, soil quality, water, weeds, pests, diseases, biodiversity and wildlife in agroecosystems (Lu et al. 2000), ecological systems managed and largely shaped by humans across a range of intensities to produce food, feed, or fiber. Cover crops are of interest in sustainable agriculture as many of them improve the sustainability of agroecosystem attributes and may also indirectly improve qualities of neighboring natural ecosystems. Farmers choose to grow and manage specific cover crop types based on their own needs and goals, influenced by the biological, environmental, social, cultural, and economic factors of the food system within which farmers operate (Snappet al. 2005). Lu, Y. C., K. B. Watkins, J. R. Teasdale, and A. A. Abdul-Baki. 2000. Cover crops in sustainable food production. Food Reviews International 16:121-157. Snapp, S. S., S. M. Swinton, R. Labarta, D. Mutch, J. R. Black, R. Leep, J. Nyiraneza, and K. O'Neil. 2005. Evaluating cover crops for benefits, costs and performance within cropping system niches. Agron. J. 97:1-11. Sumber: http://en.wikipedia.org/wiki/Cover_crops ….. Diunduh 4/3/2012
TANAMAN PENUTUP TANAH PENGELOLAAN KUALITAS TANAH Cover crops can also improve soil quality by increasing soil organic matter levels through the input of cover crop biomass over time. Increased soil organic matter enhances soil structure, as well as the water and nutrient holding and buffering capacity of soil (Patrick et al. 1957). It can also lead to increased soil carbon sequestration, which has been promoted as a strategy to help offset the rise in atmospheric carbon dioxide levels (Kuoet al. 1997, Sainjuet al. 2002, Lal 2003). Although cover crops can perform multiple functions in an agroecosystem simultaneously, they are often grown for the sole purpose of preventing soil erosion. Soil erosion is a process that can irreparably reduce the productive capacity of an agroecosystem. Dense cover crop stands physically slow down the velocity of rainfall before it contacts the soil surface, preventing soil splashing and erosive surface runoff (Romkenset al. 1990). Additionally, vast cover crop root networks help anchor the soil in place and increase soil porosity, creating suitable habitat networks for soil macrofauna (Tomlin et al. 1995). Soil quality is managed to produce optimum circumstances for crops to flourish. The principal factors of soil quality are soil salination, pH, microorganism balance and the prevention of soil contamination. Kuo, S., U. M. Sainju, and E. J. Jellum. 1997. Winter cover crop effects on soil organic carbon and carbohydrate in soil. Soil Science Society of America Journal 61:145-152. Lal, R. 2003. Offsetting global CO2 emissions by restoration of degraded soils and intensification of world agriculture and forestry. Land Degradation & Development 14:309-322. Patrick, W. H., C. B. Haddon, and J. A. Hendrix. 1957. The effects of longtime use of winter cover crops on certain physical properties of commerce loam. Soil Science Society of America 21:366-368. Romkens, M. J. M., S. N. Prasad, and F. D. Whisler. 1990. Surface sealing and infiltration. Pages 127-172 in M. G. Anderson and T. P. Butt, editors. Process studies in hillslope hydrology. John Wiley and Sons, Ltd. Sainju, U. M., B. P. Singh, and W. F. Sainju, U. M., B. P. Singh, and W. F. Whitehead. 2002. Long-term effects of tillage, cover crops, and nitrogen fertilization on organic carbon and nitrogen concentrations in sandy loam soils in Georgia, USA. Soil & Tillage Research 63:167-179. Tomlin, A. D., M. J. Shipitalo, W. M. Edwards, and R. Protz. 1995. Earthworms and their influence on soil structure and infiltration. Pages 159-183 in P. F. Hendrix, editor. Earthworm Ecology and Biogeography in North America. Lewis Pub., Boca Raton, FL. Sumber: http://en.wikipedia.org/wiki/Cover_crops ….. Diunduh 4/3/2012
TANAMAN PENUTUP TANAH PENGELOLAAN KESUBURAN TANAH One of the primary uses of cover crops is to increase soil fertility. These types of cover crops are referred to as "green manure." They are used to manage a range of soil macronutrients and micronutrients. Of the various nutrients, the impact that cover crops have on nitrogen management has received the most attention from researchers and farmers, because nitrogen is often the most limiting nutrient in crop production. Often, green manure crops are grown for a specific period, and then plowed under before reaching full maturity in order to improve soil fertility and quality. Green manure crops are commonly leguminous, meaning they are part of the Fabaceae (pea) family. This family is unique in that all of the species in it set pods, such as bean, lentil, lupins and alfalfa. Leguminous cover crops are typically high in nitrogen and can often provide the required quantity of nitrogen for crop production. In conventional farming, this nitrogen is typically applied in chemical fertilizer form. This quality of cover crops is called fertilizer replacement value (Thiessen-Martens et al. 2005). Thiessen-Martens, J. R., M. H. Entz, and J. W. Hoeppner. 2005. Legume cover crops with winter cereals in southern Manitoba: Fertilizer replacement values for oat. Canadian Journal of Plant Science 85:645-648. Sumber: http://en.wikipedia.org/wiki/Cover_crops ….. Diunduh 4/3/2012
TANAMAN PENUTUP TANAH PENGELOLAAN LENGAS TANAH By reducing soil erosion, cover crops often also reduce both the rate and quantity of water that drains off the field, which would normally pose environmental risks to waterways and ecosystems downstream (Dabneyet al. 2001). Cover crop biomass acts as a physical barrier between rainfall and the soil surface, allowing raindrops to steadily trickle down through the soil profile. Also, as stated above, cover crop root growth results in the formation of soil pores, which in addition to enhancing soil macrofauna habitat provides pathways for water to filter through the soil profile rather than draining off the field as surface flow. With increased water infiltration, the potential for soil water storage and the recharging of aquifers can be improved (Joyce et al. 2002). Just before cover crops are killed (by such practices including mowing, tilling, discing, rolling, or herbicide application) they contain a large amount of moisture. When the cover crop is incorporated into the soil, or left on the soil surface, it often increases soil moisture. In agroecosystems where water for crop production is in short supply, cover crops can be used as a mulch to conserve water by shading and cooling the soil surface. This reduces evaporation of soil moisture. In other situations farmers try to dry the soil out as quickly as possible going into the planting season. Here prolonged soil moisture conservation can be problematic. Dabney, S. M., J. A. Delgado, and D. W. Reeves. 2001. Using winter cover crops to improve soil quality and water quality. Communications in Soil Science and Plant Analysis 32:1221-1250. Joyce, B. A., W. W. Wallender, J. P. Mitchell, L. M. Huyck, S. R. Temple, P. N. Brostrom, and T. C. Hsiao. 2002. Infiltration and soil water storage under winter cover cropping in California's Sacramento Valley. Transactions of the Asae 45:315-326. Sumber: http://en.wikipedia.org/wiki/Cover_crops ….. Diunduh 4/3/2012
TANAMAN PENUTUP TANAH PENGELOLAAN GULMA Thick cover crop stands often compete well with weeds during the cover crop growth period, and can prevent most germinated weed seeds from completing their life cycle and reproducing. If the cover crop is left on the soil surface rather than incorporated into the soil as a green manure after its growth is terminated, it can form a nearly impenetrable mat. This drastically reduces light transmittance to weed seeds, which in many cases reduces weed seed germination rates (Teasdale 1993). Furthermore, even when weed seeds germinate, they often run out of stored energy for growth before building the necessary structural capacity to break through the cover crop mulch layer. This is often termed the cover crop smother effect (Kobayashi et al. 2003). Some cover crops suppress weeds both during growth and after death (Blackshawet al. 2001). During growth these cover crops compete vigorously with weeds for available space, light, and nutrients, and after death they smother the next flush of weeds by forming a mulch layer on the soil surface. For example, Blackshawet al. (2001) found that when using Melilotusofficinalis (yellow sweetclover) as a cover crop in an improved fallow system (where a fallow period is intentionally improved by any number of different management practices, including the planting of cover crops), weed biomass only constituted between 1-12% of total standing biomass at the end of the cover crop growing season. Furthermore, after cover crop termination, the yellow sweetclover residues suppressed weeds to levels 75-97% lower than in fallow (no yellow sweetclover) systems . Blackshaw, R. E., J. R. Moyer, R. C. Doram, and A. L. Boswell. 2001. Yellow sweetclover, green manure, and its residues effectively suppress weeds during fallow. Weed Science 49:406-413. Kobayashi, Y., M. Ito, and K. Suwanarak. 2003. Evaluation of smothering effect of four legume covers on Pennisetumpolystachion ssp. setosum (Swartz) Brunken. Weed Biology and Management 3:222-227. Teasdale, J. R. 1993. Interaction of light, soil moisture, and temperature with weed suppression by hairy vetch residue. Weed sci 41:46-51. Sumber: http://en.wikipedia.org/wiki/Cover_crops ….. Diunduh 4/3/2012
TANAMAN PENUTUP TANAH PENGELOLAAN PENYAKIT In the same way that allelopathic properties of cover crops can suppress weeds, they can also break disease cycles and reduce populations of bacterial and fungal diseases (Everts 2002), and parasitic nematodes (Potter et al. 1998, Vargas-Ayala et al. 2000). Species in the brassicaceae family, such as mustards, have been widely shown to suppress fungal disease populations through the release of naturally occurring toxic chemicals during the degradation of glucosinolade compounds in their plant cell tissues (Lazzeri and Manici 2001). Everts, K. L. 2002. Reduced fungicide applications and host resistance for managing three diseases in pumpkin grown on a no-till cover crop. Plant dis 86:1134-1141. Lazzeri, L., and L. M. Manici. 2001. Allelopathic effect of glucosinolate-containing plant green manure on Pythium sp and total fungal population in soil. Hortscience 36:1283-1289. Potter, M. J., K. Davies, and A. J. Rathjen. 1998. Suppressive impact of glucosinolates in Brassica vegetative tissues on root lesion nematode Pratylenchusneglectus. Journal of Chemical Ecology 24:67-80. Vargas-Ayala, R., R. Rodriguez-Kabana, G. Morgan-Jones, J. A. McInroy, and J. W. Kloepper. 2000. Shifts in soil microflora induced by velvetbean (Mucunadeeringiana) in cropping systems to control root-knot nematodes. Biological Control 17:11-22. Sumber: http://en.wikipedia.org/wiki/Cover_crops….. Diunduh 4/3/2012
TANAMAN PENUTUP TANAH PENGELOLAAN HAMA Some cover crops are used as so-called "trap crops", to attract pests away from the crop of value and toward what the pest sees as a more favorable habitat (Shelton and Badenes-Perez 2006). Trap crop areas can be established within crops, within farms, or within landscapes. In many cases the trap crop is grown during the same season as the food crop being produced. The limited area occupied by these trap crops can be treated with a pesticide once pests are drawn to the trap in large enough numbers to reduce the pest populations. In some organic systems, farmers drive over the trap crop with a large vacuum-based implement to physically pull the pests off the plants and out of the field (Kuepper and Thomas 2002). This system has been recommended for use to help control the lygus bugs in organic strawberry production (Zalomet al. 2001). Other cover crops are used to attract natural predators of pests by providing elements of their habitat. This is a form of biological control known as habitat augmentation, but achieved with the use of cover crops (Bugg and Waddington 1994). Findings on the relationship between cover crop presence and predator/pest population dynamics have been mixed, pointing toward the need for detailed information on specific cover crop types and management practices to best complement a given integrated pest management strategy. For example, the predator mite Euseiustularensis(Congdon) is known to help control the pest citrus thrips in Central California citrus orchards. Bugg, R. L., and C. Waddington. 1994. Using Cover Crops to Manage Arthropod Pests of Orchards - a Review. Agriculture Ecosystems & Environment 50:11-28. Kuepper, G., and R. Thomas. 2002. "Bug vacuums" for organic crop protection. ATTRA, Fayetteville, AR. Shelton, A. M., and E. Badenes-Perez. 2006. Concepts and applications of trap cropping in pest management. Annual Review of Entomology 51:285-308. Zalom, F. G., P. A. Phillips, N. C. Toscano, and S. Udayagiri. 2001. UC Pest Management Guidelines: Strawberry: Lygus Bug. University of California Department of Agriculture and Natural Resources, Berkeley, CA. Sumber: http://en.wikipedia.org/wiki/Cover_crops ….. Diunduh 4/3/2012
PUPUK HIJAU Green manures, often known as cover crops, are plants which are grown to improve the structure and nutrient content of the soil. They are a cheap alternative to artificial fertilisers and can be used to complement animal manures. Growing a green manure is not the same as simply growing a legume crop, such as beans, in a rotation. Green manures are usually dug into the soil when the plants are still young, before they produce any crop and often before they flower. They are grown for their green leafy material which is high in nutrients and protects the soil. If food is in very short supply it may be better to grow a legume from which a bean crop can be harvested and then dig the plant remains into the soil. These plant remains will not break down into the soil so quickly and will not be as good for the soil as younger plants but they will still add some nutrients to the soil for the next crop. Sumber: http://www.gardenorganic.org.uk/pdfs/international_programme/GreenMan.pdf ….. Diunduh 4/3/2012
ROTASI PUPUK HIJAU An example of a rotation where a legume is used as a green manure Sumber: http://www.gardenorganic.org.uk/pdfs/international_programme/GreenMan.pdf ….. Diunduh 4/3/2012
GREEN MANURES : UNDERSOWING Undersowing involves growing a green manure at the same time as a crop, among the crop plants. Sometimes they are sown with the crop or slighlty later when the crops are already growing. This reduces competition between the green manure and the crop. For example, undersowing is sometimes used with maize crops where a green manure is sown under the young maize plants. The green manure seeds are broadcast sown when the second weeding of the maize is carried out. In this way when the maize is harvested the green manure is already established and ready to grow quickly. This method means that no extra time is spent preparing the land and sowing the green manure. Sumber: http://www.gardenorganic.org.uk/pdfs/international_programme/GreenMan.pdf ….. Diunduh 4/3/2012
PUPUK HIJAU BERSAMA TANAMAN POKOK A green manure (for example a bean) sown beneath maize Tanaman pokok Pupuk hijau Sumber: http://www.gardenorganic.org.uk/pdfs/international_programme/GreenMan.pdf ….. Diunduh 4/3/2012
PUPUK HIJAU JANGKA PANJANG Green manures can be grown for more than one season and used in the following ways: • Long term green manures restore poor soil. Using them over a long time has a greater benefit on soil fertility and structure of poor soil. • Long term green manures can be used when new land is being prepared for use, especially to help control difficult perennial weeds. • Long term green manures are used where land is to have a long fallow period. They can be sown at the beginning of the fallow of bush-fallow systems. They help to quickly build up the fertility of the soil and reduce the length of time before the land can be used to grow crops again. • Long term green manures provide green material which can be cut and carried to other fields. Green material can be harvested from perennial species such as alfalfa (Medicago sativa), for digging in, mulching, composting or feeding to livestock. Sumber: http://www.gardenorganic.org.uk/pdfs/international_programme/GreenMan.pdf ….. Diunduh 4/3/2012
PUPUK HIJAU UNTUK MULSA Green manure plants can be cut and left on the soil surface as a mulch. Mulching releases nutrients slowly but has some advantages: • Mulching helps to prevent weed growth • Mulching protects the soil from erosion • Mulching keeps the soil moist by reducing evaporation. Sumber: http://www.gardenorganic.org.uk/pdfs/international_programme/GreenMan.pdf ….. Diunduh 4/3/2012
PUPUK HIJAU DALAM AGROFORESTRY Green manures in agroforestry Agroforestry is the practice of growing trees and/or shrubs together, with crops and/or animals. The trees/shrubs act as long term green manures and the leaves can be used for digging in or as a mulch. The regular pruning of agroforestry trees such as Leucaena (Leucaena leucocephala), Mother of cocoa (Gliricidia sepium) and Calliandra (Calliandra calothyrsus) during the crop growing period provides large amounts of green material for digging into the soil and reduces competition with the main crop. The material can also be used as a mulch. It is spread on the top soil, usually between crop rows or before a crop has been planted. As well as improving the soil in the ways described above, trees and shrubs also provide food, fodder, fuelwood, erosion control and other benefits. Sumber: http://www.gardenorganic.org.uk/pdfs/international_programme/GreenMan.pdf ….. Diunduh 4/3/2012
SISTEM AGROFORESTRY The benefits of nutrient cycling and erosion control in agroforestry Sumber: ….. Diunduh 4/3/2012
PEMBENAMAN PUPUK HIJAU Digging in green manures Before a crop is sown the green manure is dug back into the soil. Here it decomposes and the nutrients held inside green manure plants are released. • The plants take a short time, usually about two weeks, to rot down into the soil before the next crop is sown. • Green manures should not be ploughed in as this buries the plants and the nutrients too deep. They should be turned in just under the soil surface. • Digging is easier if the plants have been chopped into small pieces before digging. This also helps prevent the problem of regrowth if this should occur. • If digging-in is difficult the plants can be dug in roughly, left for a few days and dug over again. Sumber: ….. Diunduh 4/3/2012
PEMILIHAN PUPUK HJIJAU When choosing which green manure plant to use, you should consider the following points: A green manure must suit the local climate, and the soil that it is to be sown in. This will help to keep the green manure healthy and to keep pests and diseases to a minimum. Fast growing and leafy green manures are often preferred as they provide more nutrients when dug in. Green manures should not be closely related to the following crop as they could attract pests and diseases which may affect the following crop. It is important to know whether seed is easily available and affordable. The length of time that land is free and how long the green manure will take to grow. Plants which can be grown as a green manure include legumes and non-legumes. Legumes have nodules on their roots which contain bacteria. These bacteria take nitrogen from the air. This is known as ‘nitrogen-fixation’. Plants use this to grow, but this extra nitrogen is also made available to future crops when the legumes are dug into the soil. The ability of legumes to ‘fix’ nitrogen makes them very good green manures. However they do have limitations and non-legumes can sometimes be more suitable. Sumber: http://www.gardenorganic.org.uk/pdfs/international_programme/GreenMan.pdf ….. Diunduh 4/3/2012