Biomass Yield, Quality, and Soil Nutrients of Pasture Influenced by Farmyard Manure and Enrichment Planting

Abstract

Grazing land remains the major feed source for livestock for smallholder farmers in Ethiopia; however, its productivity is low and it is prone to degradation. A field experiment was conducted to evaluate the effects of farmyard manure (FYM) and enrichment planting with improved forages on biomass yield, nutritional value, and soil chemical properties in dryland areas of northwestern Ethiopia. The experiment was carried out using a randomized complete block design with three replications for 2 yr. Natural pasture plots were seeded and treated with Napier grass (Pennisetum purpureum) or desho grass (Pennisetum pedicellatum), Napier or desho + FYM, Napier or desho + Desmodium, and Napier or desho + FYM + Desmodium; untreated plots were used as controls. In the yr 2019, after treatment application the overall herbaceous species identified in the experimental plots were grasses (64%), legumes (22%), and forbs (14%). In all treatment groups, legumes dominate in the first yr while grasses dominate in the second yr. Within treatment groups, dry matter yield (DMY) increment was recorded from the first yr to the second yr, by values ranging from 2.9% to 23.0%. The mean DMY in the desho + FYM + Desmodium uncinatum plots (8.4 t ha−1) was higher (P < 0.001) than controls (4.4 t ha−1). Natural pasture treated with Napier or desho in conjunction with either Desmodium or FYM and their combinations had a higher crude protein content (P < 0.001) than natural pasture alone despite the fact that in vitro organic matter digestibility was higher in desho grass when combined with desmodium or FYM treatments. Plots treated with Napier + FYM, Napier + Desmodium, and desho + Desmodium + FYM showed organic carbon levels that were significantly (P < 0.001) higher than the controls. Overall, desho + FYM + Desmodium produced the greatest improvement in grazing land productivity by maintaining soil fertility.