Zaady E.,Israel Agricultural Research Organization |
Arbel S.,Soil Erosion Research Station |
Barkai D.,Israel Agricultural Research Organization |
Sarig S.,The Katif Research Center
Journal of Arid Environments | Year: 2013
The natural landscapes of semiarid areas worldwide comprise a series of scattered patches of shrubs within a matrix of biologically crusted soils (BSC). As BSCs are considered ecosystem engineers the relationships between the BSC and the shrub patches determine system functioning. The objective of our study was to investigate long-term effects of agricultural practices on biological soil crusts and their influence on hydrological aspects of a semiarid ecosystem. During 1991, we experimentally simulated five of the area's agricultural practices; 1) Scraping - the topsoil was removed to a depth of 2 cm, 2) Spraying - phototrophic organisms were chemically killed with herbicide, 3) Mowing - perennial vegetation was cut and spread to simulate grazing practices, 4) Car track - a heavy roller was used to simulate car-tracks, 5) Control - undisturbed natural plots. Sixteen years later, in 2007, these agricultural practices were found to have a long-term effect on the crusted soil surface and the related soil-surface properties. Mowing and car-track treatments led to decreased overland runoff and increased hydraulic conductivity, whereas scraping and spraying treatments led to increased overland runoff production and decreased hydraulic conductivity. We conclude that the practices had a long-term residual impact on BSC succession and related soil surface properties, which affected the hydrological processes and system functioning. © 2012 Elsevier Ltd.
Bar-Yosef B.,The Katif Research Center |
Ben Asher J.,The Katif Research Center
Journal of Plant Nutrition and Soil Science | Year: 2013
The impact of horticultural management on carbon sequestration in soils has been limited so far to tillage and nitrogen fertilization. Our objective was to evaluate by mathematical modeling the effect of potassium fertilization on CO2 binding in cropland soils. The developed model integrates three subunits: (1) A published simulator of crop dry-matter (DM) production in response to N, P, K fertilization, but not DM partitioning; (2) a published soil-crop-atmosphere model predicting crop yield and DM partitioning as a function of N but not K fertilization; (3) an original model computing the organic-inorganic carbon transformations, inorganic-carbon reactions and transport in soil, CO2 diffusion, and soil carbon sequestration. The model described the K-fertilization effect on C binding in soil as a function of the soil pH, the Ca2+ concentration in the soil solution, hydraulic properties, air temperature, and crop DM production, and partitioning characteristics. In scenarios of corn (Zea mays L.) growth in clayey soil and wheat (Triticum aestivum L.) in loam soil, the computed K-induced CO2 sequestration amounted to ≈14.5 and 24kg CO2 (kg K)-1, respectively (0 vs. 100kg ha-1 K application). The soil CO2 sequestration declined by 8% when corn grew in sandy instead of clayey soil and by 20% when the temperature was 10°C higher than the temperature prevailing in mild semiarid zones. All predicted CO2-sequestration results were approximately 30-fold higher than the 0.6kg CO2 emitted perkg of K manufactured in industry. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.