Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/1/2004
Publication Date: 11/1/2004
Citation: Acosta Martinez, V., Allen, V. 2004. Soil microbial, chemical and physical properties in continuous cotton and integrated crop-livestock systems. Soil Science Society of America Journal. 68(6): 1875-1884. Interpretive Summary: Recently, interest has focused on developing more environmentally and economically possible crop-livestock systems that will guarantee agricultural activities on the Texas High Plains of the USA. This study evaluated a Conventional Cotton System and an Alternative Integrated Crop-Livestock System at the Texas Tech University Agricultural Field Laboratory near New Deal, TX, by investigating their soil properties. The Alternative Integrated Crop-Livestock System was represented by a constant perennial pasture, rye-cotton-wheat rotation, and wheat-fallow-rye rotation, and the Conventional Cotton System was represented by continuous cotton. After five years, organic C, microbial biomass C and N, fungi (fatty acids) indicators, and enzyme activities were increased at 0-5 cm soil depth in perennial pasture and wheat-fallow-rye rotation in comparison to continuous cotton. Studies on an important enzyme activity for S cycling in soil reflected that living microorganisms was the more predominant source of this enzyme in this semiarid soil in comparison to the enzymes attached in soil, and thus, not related to living microorganisms. Microbial biomass C and N and beta-glucosaminidase activity were increased at 5-10 cm soil depth in the perennial pasture and wheat-fallow-rye rotation compared to continuous cotton while organic C and total N remained similar among the systems. The increases in microbial biomass C and N, fungi indicators, and enzyme activities under the alternative systems studied must be due to its greater surface cover, and more diverse amounts of organic substrates available in soil relative to the low-crop residue system of continuous cotton, and they are anticipating changes that may occur to other soil properties.
Technical Abstract: Recent efforts in the Texas High Plains of the USA are focused on developing more environmentally sustainable and economically feasible crop and livestock production systems that will assure the viability of agricultural activities. We investigated selected chemical, physical, and microbiological properties of a Pullman soil (fine, mixed, thermic Torrertic Paleustolls with 38% clay, 28% silt, and 34% sand) under a Conventional Cotton System and an Alternative Integrated Crop Livestock System for 5 years. The study was located at the Texas Tech University Agricultural Field Laboratory near New Deal, TX. Soil samples (0-5, 5-10, 10-15 cm) were taken in November 2002 from constant perennial pasture, rye-cotton-wheat rotation, and wheat-fallow-rye rotation (Alternative Integrated Crop-Livestock System) and from continuous cotton (Conventional Cotton System). Organic C, microbial biomass C and N, fungi fatty acids indicators, and the activities of beta-glucosaminidase, beta-glucosidase, and arylsulfatase were increased at 0-5 cm depth in perennial pasture and wheat-fallow-rye rotation in comparison to continuous cotton. An increase in the intracellular and extracellular arylsulfatase activity, and on arylsulfatase protein content in soils under alternative systems was found at 0-5 depth compared to continuous cotton by using new methods available for these determinations. Microbial biomass C and N and beta-glucosaminidase activity were increased at 5-10 cm depth in the alternative systems compared to continuous cotton while organic C and total N remained similar among the systems. This study demonstrated the benefits in microbiological and chemical properties in a semiarid soil after five years caused by greater diversity and amounts of organic substrates under pasture and wheat-fallow-rye rotation compared to the lower crop residue system of continuous cotton.