Effect of livestock manure on soil microbial and nutrient dynamics in zaï cropping systems of the Sahel

Abstract

AbstractThe zaï cropping system that involves precision manure placement in small excavated soil pits is designed to restore the productivity of encrusted and degraded soils of the Sahel. However, there is little information on the effectiveness of zaï cropping to improve soil quality, particularly as to how it relates to manure sources. Therefore, our objective was to determine the effect of manure type on plant nutrient availability and soil microbial activity in relation to crop productivity. The experiment had a randomized block design with the following treatments with all manure amendments applied at 6 Mg ha−1: 1) sheep (Ovis aries), 2) goats (Capra hircus), and 3) cattle (Bos indicus) manures; 4) an equal mix of all three manures; and 5) a control with no manure amendment ‐ after which sorghum (Sorghum bicolor [L.] Moench) was planted. Soil samples (0–20 cm) were taken from zaï pits at the sorghum boot stage and analyzed for a suite of plant‐available nutrients, microbial composition, and enzyme activities. The results showed that the zaï system with manure amendments significantly increased soil pH, plant‐available nitrogen by three‐fold, and phosphorus by two‐fold over the control. Goat or mixed manure amended soils had significantly higher enzyme activities than sheep or cattle manure. Manure type also shifted the EL‐FAME biomarkers for bacteria, fungi, and protozoa indicating a more favorable copiotrophic environment in manure amended soils. zaï cropping systems amended with the higher quality or the mixed manure had greater microbial responses, nutrient availability, and crop productivity than the lower quality manure.