Short‐Term Effects of Land Leveling on Soil Chemical Properties and Their Relationships with Microbial Biomass

Abstract

Spatial variability and distributions of soil chemical properties and the relationships between soil chemical and biological properties are not well characterized in agroecosystems that have been land leveled to facilitate more uniform delivery of irrigation water. The objectives of this study were to characterize the short‐term impacts of land leveling on the magnitudes, spatial variability, and spatial distributions of soil chemical properties and to evaluate the impact of land leveling on the relationships between soil chemical properties and microbial biomass in a Stuttgart silt loam (fine, smectitic, thermic Albaqultic Hapludalf) used for irrigated soybean [Glycine max (L.) Merr.] and rice (Oryza sativa L.) production in the Mississippi Delta region of eastern Arkansas. A grid‐sampling approach was used to characterize pre‐ and postleveling soil chemical properties and microbial biomass. Results of this study demonstrate that land leveling, a severe form of anthropogenic soil disturbance, causes significant alteration of the magnitudes, spatial variability, and spatial distributions of many soil chemical properties. Soil electrical conductivity (EC) and the contents of P, K, Mg, Na, S, Mn, and Cu in the top 10 cm significantly increased, while soil pH and organic matter (OM) and Fe contents significantly decreased, as a result of land leveling. Land leveling also significantly altered many linear relationships among soil chemical properties and microbial biomass. The benefit of improved water distribution must be weighed against the relatively severe and immediate alteration of soil properties and natural processes brought on by land leveling. Further research is required to ascertain long‐term effects of altered soil biogeochemical properties on crop growth as a result of land leveling.

Spatial variability of the chemical, physical and biological properties in lowland cultivated with irrigated rice

“…The same behavior was found for the soil properties Tp, EC, P, Ca 2+ , Mg 2+ , Fe, Mn, Na, and MBC. However, under these circumstances, it may be affirmed, based on the determined dependence structures that the observations of each one of these properties depend on each other within the studied domain (Brye et al, 2004). Nielsen & Wendroth (2003) emphasize that the nugget effect may occur in the following situations: error in the laboratory process of soil sampling and laboratory analysis or due to the fact that the magnitude of spatial dependence is lower than the shortest distance between the sampled grid points (here 10 m), or possibly due to a combination of both situations.…”

Spatial variability of soil carbon, nitrogen, and phosphorus content and storage in an alpine wetland in the Qinghai - Tibet Plateau, China

“…The spatial variations of SOCD, STND, and STPD were large, with the coefficients of variation (CV) of >30% (Table 2). Although the CV is an index of the overall variation or heterogeneity of a given variable, the statistical analyses could not discern quantitative changes in spatial patterns (Brye et al 2004). Therefore, the spatial variations of SOCD, STND, and STPD were assessed using geostatistical analysis and kriging techniques.…”

Effects of land uses on solid-phase distribution of micronutrients in selected vertisols of the Mississippi River Delta

“…It was reported that eastern Arkansas silt-loam soils made alkaline from the use of high carbonate-containing irrigation water, and the availability of micronutrients generally decreases as soil pH increases (Norman et al, 2003). Land leveling frequently decreases bioavailability of Zn in these soils (Brye et al, 2004;Brye, 2006). Rice yields have been shown to increase on these soils when fertilized with inorganic N, P, and Zn (Miller, 1990;Miller et al, , 1991.…”