Productivity improvement of bread wheat (Triticum aestivum L.) through crop rotation and organic matter application in degraded crop farms of Ethiopian highlands

Abstract

AbstractBread wheat is one of the most important staple crops in Ethiopia and it is largely produced by smallholder farmers in the highlands of the country. Its productivity is, however, very low below the world average mainly due to the dwindling of soil productivity and depletion of soil fertility as the result of complete removal of crop residues as well as abandoning of crop rotation and organic matter application. Hence, a 3 years experiment was conducted to study the productivity improvement of bread wheat through crop rotation and organic manure application in degraded crop fields of Ethiopian highlands. Both at station and on-farm sites, factorial combinations of five crop rotations (R1+ = bread wheat–clover–potato, R2+ = clover–bread wheat undersowing lupine–potato, R3+ = potato–clover–bread wheat, R4+ = bread wheat undersowing lupine–potato undersowing lupine–bread wheat and R5+ = lupine–potato undersowing lupine–bread wheat) and four manure application rates [M1 = control/without manure, M2 = 2.5 t ha−1 Sesbania green manure (SGM), M3 = 5 t ha−1 fresh cattle manure (FCM) and M4 = 2.5 t ha−1 SGM + 5 t ha−1 FCM] were laid out in a randomized complete block design with four replications. Crop rotation treatments with plus sign (+) indicated that crop residues and/or green manure of preceding crops were incorporated into the soil. Sole bread wheat crop (R1) without manure application (M1) in the first year (2013) was considered as the control and baseline of the study. Results of the study clearly showed that the interaction of R3+ and M4 in 3 years period (2013–2015) enabled to recover the highest grain productivity of bread wheat from 0.95 and 0.69 to 4.83 and 4.14 t ha−1 with the percentile increments of 408.42 and 500.00% at station and on-farm sites, respectively. Thus, long-term application of organic manure with moderate quantity and incorporation of crop residues in pragmatic crop rotation of a vigorous legume before wheat have great potentials for recovering the productivity of bread wheat in degraded crop fields.