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Understanding the dependence of soil respiration (Rs) on land use can improve our understanding of global carbon dioxide fluxes and provide useful information for designing land management options. In this study, we examine the spatiotemporal variability of Rs and the factors that influence it. Mean Rs was significantly higher (p< 0.05) in the teff farmland (TC) and khat plantation (KP) than in grazing land (GL) in the midland; Rs rates were significantly higher (p< 0.05) in GL than A. decurrens (AP)and TC in the highland area. In the highlands, seasonal variation of Rs was significantly (p< 0.05) greater in autumn in GL than in TC and AP, but in winter, Rs varied significantly (p< 0.05) more in AP than in TC and GL. In the midland, TC had significantly (p< 0.05) higher Rs than GL in autumn. In addition, TC and KP had significantly higher Rs than GL in winter and spring. In the highlands, STexplained 0.02–45% Rs variation using the exponential model; however, in the midlands, STexplained 5–28%. In the midland, the quadratic function explained 32–89% of the variation in the seasonal Rs rates based on SM, while in the highlands, it explained 11–66%. Moreover, multiple regressions explained 57–80% of the variation in annual Rs rates in midlands based on STand SM, while they explained only 12–32% in the highlands. Thus, Rs was mainly influenced by environmental factors, although it varied spatially and temporally.

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 two years. 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 year 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 year while grasses in the second year. Within treatment groups, dry matter yield (DMY) increment was recorded from the first year to the second year, by values ranging from 2.9%–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 + Desmodiumproduced the greatest improvement in grazing land productivity by maintaining soil fertility.