Effect of Organic Mulching on in-situ Soil Moisture Conservation, Yield, and Yield Attributes of Soybean (Glycine max (L). Merrill) in the Semi-arid Areas of Western Tigray, Ethiopia

Abstract

Soybean (Glycine max (L.) Merr.) is widely cultivated in tropical, subtropical, warm temperate and semi-arid regions. However, its productivity remains low because of several biotic and abiotic constraints. Soil moisture stress is a major abiotic constraint that causes extensive losses in soybean production. Therefore, this study aimed to investigate the effect of organic mulching on soybean productivity and in situ soil moisture conservation. The study was conducted at Humera Agricultural Research Center during the 2020 main cropping season under rainfed conditions using a randomised complete block design with three replications. Five mulching rates (no mulch, 5 t ha-1, 10 t ha-1, 15 t ha-1 and 20 t ha-1) were considered as treatments, and the Hawassa-95 soybean variety was used. The results showed that the highest soil moisture was conserved under 20 t ha-1 mulch at all soil depths (0-0.2 m, 0.2-0.4 m and 0.4-0.6 m) during 15-90 days after sowing. Likewise, the highest hundred-seed weight (11.69 g), grain yield (1611 kg ha-1) and harvest index (38.48%) were recorded under the 15 t ha-1 mulch treatment. Although 15 t ha-1 mulch cover had positive effects on soil moisture conservation and soybean production, the economic analysis showed that 10 t ha-1 was the most profitable treatment, with a marginal rate of return of 706%. Therefore, farmers are advised to apply 10 t ha-1 mulch to improve soybean production and profitability.