Effects of storage methods on chemical composition of manure and manure decomposition in soil in small-scale Kenyan systems

As a soil amendment, cattle manure enhances soil mineral N content if managed correctly. Manure management varies among smallholder Kenyan farms, yet the quality of manure produced by different methods has not been assessed. This study examined the effects of storage method on the manure N composition and degradability in the soil. Nitrogen composition of manure from cattle fed high and low quality diets, stored under different containment, shading, and manure addition methods was monitored for 30 days. Manure aged 30 days was buried in soil in large- and small mesh litterbags. The disappearance of organic N was monitored over 112 days. Time in storage (P < 0.03) and farm of origin (P < 0.0001) were the only variables to influence manure organic N content. Origin (P < 0.04) and time in storage (P < 0.0001) were also the only variables that affected manure mineral N content. Manure N derived from cows fed a higher quality food (Medium quality manure) disappeared faster than manure N derived from cows fed a lower quality food (Low quality manure). More N may be available for uptake by plants during one growing season if manure from better-fed cattle is used as a soil amendment.

Research highlights▶ Much of manure mineral N lost by 30 days in storage. ▶ Manure storage techniques such as shading, piling, and placing in pits had no effect on manure composition. ▶ Cattle diet may affect manure N release in soil.