Area of Study

1. Variation of Biochemical Properties with the Use of Soil in Steppic Areas of Northern Castile (Spain) Carlos Rad*, Daniel Pérez-Alonso, Julio Arroyo, Salvador González-Carcedo Edaphology and Agricultural Sciences. University of Burgos. Faculty of Sciences. Misael Bañuelos Sq. 09001 Burgos. Castile (Spain) Author for correspondence: *crad@ubu.es Introduction Area of Study Twenty top soil samples (0-10 cm) of these areas, corresponding to three main uses: cultures, pastures or abandoned lands and derelict forests, were taken in spring and autumn 2000. • The aim of this work is to characterise the soils of the cereal steppes of the Northern Castilian plateau in terms of their physical, chemical and biochemical properties: • Selected sampling areas has been chosen corresponding to extensive cereal crops, pasturelands or derelict forests • The variation in the biochemical parameters have been put in relation with soil physical and chemical properties, the soil use or the sampling season. • Its final objective is to show that the biochemical soil properties could respond sensitively to the environmental or edaphic changes, giving current information on soil status. (7) Villalta Wheat culture (A7C) Pasture land (A7P) Oak Forest Q. pirenaica (A7F1) Pine Plantation P. sylvestris (A7F2) Area of Study (6) Cernégula A7 Wheat culture (A6C) Wetland (A6P) Oak Forest Q. ilex (A6F) City of Burgos A6 A5 (2) Rabé de las Calzadas Material and Methods (5) Hontomín Barley culture (A2C) Pasture land (A2P1) Fallow 5 years (A2P2) Fallow 20 years (A2P3) Oak Forest Q. faginea (A2F) Wheat culture (A5C) Oak Forest Q. pyrenaica (A5F) • Physical properties: particle density, water retention and the soil texture. • Chemical parameters (Sparks et al., 1996): pH (ph), Electrical Conductivity (ec), Organic Matter (om), Total N (nt), Total Phosphorus (p_t), Inorganic Phosphorus (p_i) and lime. Labile C (c_lab) and N (n_lab). • Biochemical parameters: acid (ac_pa) and alkaline phosphatases (alk_pa) and -D-glucosidase (b_glu), dehydrogenase (dha), arginine deaminase (arg) and Biomass N (n_bio). • The analysis of the variance was performed using the one-way ANOVA method with sample season and soil uses as contrast factors; Fisher's Least Significant Difference (LSD) was used to obtain the mean values that differed significantly from the others. • Multivariate analyses (PCA and RDA) have been performed with the programme CANOCO 4.5 (ter Braak and Smilauer, 2002). A4 A3 (4) Villaverde Peñahorada Oak Forest Q. ilex (A4F) A2 A1 (3) Arroyal (1) Villasur de Herreros Pasture land (A3P) Barley culture (A3C1) Barley culture+Sewage Sludge (A3C2) Horticultural soil (A1C) Oak Forest Q. pyrenaica (A1F) Figure 1 Cultured soils showed negative gradients for all biochemical properties, opposite to the natural soils, forest or pastures. Cultured soils displayed strong negative gradients with the organic matter content and positive gradients with lime and inorganic P as a consequence of an exclusive inorganic fertilization. Results and Discussion Figure 2 Soil samples from autumn are strongly influenced by the arginine deaminase activity as a consequence of the mineralization of organic inputs. Samples from spring by both phosphatases and dehydrogenase reflecting the increase of soil microbial activity and the release of nutrient such as phosphate. Table 1 Mean values for the biochemical soil parameters for soil sampling season and the different soil uses. Means with the same letter do not differ significantly. • Mean values for the biochemical parameters in cultured soils are lesser than for soils in pastures and these lesser than forest soils, except for β-glucosidases and alkaline phosphatases in which the highest activity was found in pasturelands. • Traditional agricultural practices in this area associated to extensive cereal cultivation, such as no organic amendments addition, an exclusive inorganic fertilisation, the use of agrochemicals and the burning of crop residues after harvest, have had an important negative effect in the conservation of soil biological activity that is reflected by the low values of their biochemical properties. SPECIES ENV. VARIABLES Figure 3 The ordination diagram of RDA showed closed ordination between organic matter and the biomass contents, between total and labile N and different enzyme activities such as dehydrogenase, arginine deaminase or acid phosphatase and also, between soil labile C, alkaline phosphatase and β-glucosidase activities. c_n 0.8 0.6 n_bio om 0.4 0.2 Axis 2 dha arg 0.0 ac_pa n_lab p_t nt b_glu ph p_i -0.2 lime alk_pa ec c_lab -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 Axis 1 Conclusions References Bending, G.D., Turner, M.K., Rayns, F., Marx, M.-C., Wood, M. (2004) Microbial and biochemical soil quality indicators and their potential for differentiating areas under contrasting agricultural management regimes. Soil Biol. Biochem. 36, 1785-1792. Gil-Sotres, F., Trasar-Cepeda, C., Leiros, M.C., Seoane, S. (2005) Different approaches to evaluating soil quality using biochemical properties. Soil Biol. Biochem. 37, 877-887. Nannipieri, P., Grecco, S., Ceccanti, B. (1990) Ecological significance of the biological activity in soil. In: Soil Biochemistry. Stotzky, G., Bollag, J.M. (Eds.) Marcel Dekker, New York, pp. 233-255. Sparks, D.L., Page, A.L., Helmke, P.A., Loeppert, R.H., Soltanpour, P.N., Tabatabai, M.A., Johnson, C.T., Sumner, M.E. (1996) Methods of Soil Analysis: Part 3-Chemical Methods. SSSA 5, Madison, WI, 1358 pp. ter Braak, C.J.F., Smilauer, P. (2002) CANOCO Reference Manual and CanoDraw for Windows User's Guide: Software for Canonical Community Ordination (Version 4.5). Microcomputer Power, Ithaca, NY, 500 pp. • Soil biochemical properties could reflect the negative influence of cultivation practices or the recovery of the natural biological status of the soil after the abandonment of the activity, reaching similar levels to those displayed in forest soils in the same area. • Different patterns for the soil enzymatic activities were obtained in function of the sample season or the predominant soil use, that could be useful to interpret the complex metabolic mechanisms involved in soil biological processes.