Benefits of Organic Farming Practices on Crop Water Use Efficiency in Arid Regions

1. Benefits of Organic Farming Practiceson Crop Water Use Efficiency in Arid Regions By Khaled Negm

2. The Speaker • B. Sc. OrganicAgricultural Sciences • M. Sc. Integrated Water Resources Management withspecialfocus on Middle East and Northern Africa Region (IWRM MENA) • Currentjob: Senior researcher and projectcoordinator at INWRDAM • Area of expertise: Sustainable agriculture, organic agriculture in the tropics and subtropics, IWRM, Rural development processes…

3. Outline • Introduction • Arid Agriculture - problems, obstacles and challenges • Nutrient leaching, run-off, groundwater and irrigation associated salinity • Water resources use and crop water use efficiency in arid regions • Organic farming practices • Conclusion

4. Abstract • “Climate change impacts will hit arid regions the hardest. The current situation of agriculture in arid regions is quite severe: Low soil fertility, high rates of land degradation, water scarcity, low water quality and increasing rates of soil and water salinity make agricultural production often impossible. Excessive irrigation and mining of aquifers result in extremely high salinity rates. Organic agriculture promotes soil fertility, biodiversity, closed nutrient cycles and a diverse range of crops through a holistic system approach, which gives an opportunity to cope with the current obstacles in arid agricultural regions and to increase crop water use efficiency significantly.”

5. Introduction • Around 2.6 billion people live in areas that are affected by drought and desertification • Nearly 1.2 billion people are facing the severe problems of water scarcity. • Natural regeneration process of vegetation and soil takes 5-10 times longer in arid regions than in humid regions (Gabathuler et al., 2009) • Constantly growing population  food security • Physical and demographic challenges  high poverty levels, unemployment, increasing migration to cities, urbanization, extreme water scarcity and land degradation • These challenges are going to be worse due to climate change with increasing biophysical and non-biophysical obstacles (CGIAR, 2013)

6. Main biophysical obstacles are land degradation, limitations of natural resources, advancing desertification, water scarcity and soil salinization through inadequate irrigation techniques • Non-biophysical challenges include an inequitable access to land, water and markets. • Prediction of nearly all global climate circulation models from the last 20 years give evidence that arid regions will have the highest climate change impacts, especially North and sub-Sahara African regions, and West Asia regions (CGIAR, 2013)

7. Organic Farming • (IFOAM) “A production system that sustains the health of soils, ecosystems and people relying on ecological processes, biodiversity and cycles adapted to local conditions, rather than the use of inputs with adverse effects. It combines tradition, innovation and science to benefit the shared environment and promote fair relationships and a good quality of life for all involved."

8. Cropwateruseefficiency • Crop yield (in kg)/consumptive use of water (evapotranspiration) by the crop (in mm)

9. Arid Agriculture - problems, obstacles and challenges • Water is the limiting factor in arid regions  restricted agricultural crop production • Main challenge in arid agricultural production systems: managing water scarcity and water quality • Arid agricultural production systems often fully depend on irrigation • By excessive and inappropriate use of irrigation water and mining of aquifers, salinity of soil, surrounding water resources and groundwater occurs • Moreover, through intensive and unsustainable high input agricultural practices, soil fertility loss, loss of organic matter, soil erosion and compaction develop • Nevertheless, arid regions provide vast undeveloped areas, where high yielding crop production is possible when access to water exists. Favorable conditions like warm temperatures and high solar radiation increases crop productivity. • Due to the harsh climatic conditions, pests and disease pressure are relatively low compared to humid regions(Ben-Gal et al., 2006; Creswell & Martin, 1998)

10. Nutrient leaching, run-off, groundwater and irrigation associated salinity • The most important agricultural nutrients (water quality and human health)  nitrate and phosphorus • Due to its negative charge, nitrate, the prevalent form of nitrogen in soils, is prone to leaching • In arid regions, sandy and silty soils with low organic matter are predominant, thus the ability to hold and absorb nutrients is restricted and they get easily transported via the soil into the groundwater. When excessive improper irrigation is done after a long period of drought, silted soil surface prevent water from infiltrating into the soil and exacerbates runoff with soil nitrate and phosphorus (Bellows, 2002)

11. Salinization describes the accumulation of watersoluble salts in the soil layers which affects the agricultural production and the ecosystem • The main reasons are: an accelerating use of low quality water, inappropriate cultural practices and the shortage of organic matter (Vengosh, 2007; Lakhdar et al., 2009) • Salinization can be driven by natural phenomena and human activities. Natural inputs of salt in soils include rainfall, aeolian deposits, stored salts in soils and accumulated groundwater salts • 2 major types of salinity: Groundwater associated salinity and irrigated associated salinity • Groundwater associated salinity on the one hand gets triggered by discharged areas where water ascends from the groundwater to the soil, carrying dissolved salts. The upward movement of water and salts is driven by the evaporation from soil and the transpiration of the plant • Irrigation associated salinity on the other hand is induced by irrigation water that is then kept in the root zone because of poor leaching. Factors that increase irrigation induced salinity are poor quality irrigation water, low hydraulic conductivity plus high evaporative conditions. In addition to that, highly saline effluent water, missing drainage and soil management techniques accelerate the effect. In arid regions often both, groundwater associated salinity and irrigation associated salinity do occur, which intensifies the effect (Rengasamy, 2006)

13. Water resources use and crop water use efficiency in arid regions • Most important: Protection of given water resources and their sustainable and responsible usage (Ben-Gal et al., 2006) • Highest priority: water collection, water saving and soil moisture techniques (Kilcher, 2007) • Unfortunately, current water resources use is characterized by excessive irrigation patterns • Traditional water resources use include harvesting of runoff of irregular storms, groundwater use by wells and currently the reuse of wastewater and desalinization schemes • Each use offers opportunities, but also challenges • For instance, the reuse of wasted water is now commonly adopted in arid agriculture • Three main concerns: (1) human health, (2) harmful effects to plant growth and soil and (3) groundwater deterioration • Treated effluents often carry high concentrations of contaminants like mineral ions, including salts and specific toxic ions • A meticulous process for irrigation  prevent soil salinization and land degradation. • Effluents from wasted water plants can be used for irrigation and fertilization of cropland • The process of desalinization to produce fresh water out of brackish groundwater and seawater is still at its initial phase with high energy demand and connected with ecological concerns (Ben-Gal et al., 2006)

14. Overall goal not just to stabilize the yield, but to increase the yield potential • Unfortunately, in a water scarce environment with poor soil conditions it is quite difficult to expand the given yield potential • In most breeding programs for arid crops, the focus is set on drought resistance, which is not compatible with a high yield potential • Furthermore, a carefully reduced water use, which is recommended for arid agricultural production systems, lowers the yield potential as well (Blum, 2005) • Focus must be set on the improvement of crop water use efficiency by soil water conservation practices. • Analysis of the interaction between precipitation, evaporation and the resulting water regime which determines mainly the productivity and management of crops in arid regions • Water balance approach including the analysis of rainfall and irrigation patterns, crop water requirements, soil water storage and evaporation rates, can help to assess the water regime of the system(Ethan & Umar, 2001) • Accordingly, "more crop per drop" can be accomplished by certain crop and soil management practices (Blum, 2009)

15. Organic farming practices • Main objectives : improvement of soil fertility, conservation of biodiversity, to adapt production methods according to locally available resources, prevention of chemical inputs, closed nutrient cycles on farm level, diverse range of crops and control of pests and diseases by natural antagonists (Kilcher, 2007) • Several organic farming practices: compost systems, agroforestry, intercropping techniques, crop rotation, conservation of agricultural techniques, cover crops, mulching, using legume plants, efficient irrigation techniques, crop, and variety selection, and a general biodiversity, which contribute to the above-mentioned objectives (Creswell & Martin, 1998; Kilcher, 2007)

16. Compostingadvantages • As plants are not able to take up nutrients from manure and crop materials directly, soil organisms like beetles, earworms, fungi, bacteria and nematodes help to decompose and release the nutrients in a form possible for the plant to absorb them • Composting is also an aspect of organic farming which produces organic fertilizer from decomposed agricultural materials. The rate of composting is determined by the temperature and moisture which influences the time for the soil organisms and amount to decompose and release the nutrients. Best conditions for soil organism to decompose the available material are warm temperatures, moist conditions, and a neutral pH (Bellows, 2002) • Composting systems implemented in an arid agricultural production scheme offer a wide range of benefits. As in arid regions a shortage of organic fertilizer input occurs and organic farming depends on it. Composting is a possible solution to convert agricultural waste materials to a useful resource. The following benefits have been reported: enrichment of soil fertility, soil health, improvement of soil biodiversity, elimination of weed seeds, and pathogenic microorganisms and high cost effectiveness (Aziz, 2014).

21. Agroforestry, a production system where trees and shrubs are combined with crops, offers huge opportunities, especially in the agriculture of arid regions. Implemented agroforestry systems provide a more stable ecological system. Furthermore, it improves soil fertility, offers Nfixation by legume trees, protects the soil against erosion and weeds, provides shade and by that preserves soil humidity. Additionally, it makes a high diversity of plants possible and offers micro climatic effects (Kilcher, 2007) • Intercropping practices, crop rotations and cover crops are useful tools in organic agriculture; they enable crop diversity, raise soil fertility, increase efficiency for nutrient uptake by plants, reduce pest pressures, manage erosion and enhance water absorption • Conservation agricultural methods like minimum tillage techniques help the soil to restore itself, keep soil humidity and decrease the potential for water runoff and wind and water erosion. Implementation of mulching reduces evaporation and soil loss due to wind. In the harsh climatic conditions of arid regions, it is furthermore advisable to use adapted crop varieties, which can withstand high temperatures and seasonal droughts (Bellows, 2002; Creswell & Martin, 1998)

24. Conclusion • Organic farming practices offer a wide range of solutions to the current obstacles in arid agricultural production schemes and can furthermore improve crop water use efficiency significantly • Main problems in the arid agricultural regions of the world are high water scarcity levels, low water quality and increasing water, soil salinization and land degradation. Organic farming practices enable the implementation of high levels of soil organic matter and soil organisms, which are essential for an effective crop production and protection of water resources • It is necessary to improve the water use efficiency, by using more water saving technologies that prevent soil and water salinization • This may require a shift to more modern technologies, such as micro-sprinkler and drip irrigation systems that use carefully controlled application of water • This may be an expensive cost for smallholder farmers, which account for a high percentage of arid farmers and hence, government incentives should be encouraged to help them meet this target. To implement organic farming practices successfully, ongoing monitoring and management are needed. The possibility to counteract land degradation and desertification processes by compost system implementation requires more scientific research.