EFFECTS OF STRAW MULCH AND MANURE ON MOISTURE CONSERVATION AND YIELD AND YIELD COMPONENTS OF MAIZE (Zea mays L.) AT THE MID RIFT VALLEY OF OROMIA, ETHIOPIA

Abstract

Water shortage is one of the major problems limiting crop productivity in arid and semi-arid regions. Suitable soil and water conservation measures that can be easily integrated into the existing farming operations while enhancing in-situ moisture conservation by reducing the direct impact of raindrops, maintaining soil infiltration, increasing surface storage and affecting soil temperature, and increasing nutrient is crucially needed. A field experiment was conducted under natural rainfall conditions to investigate the effects of straw mulch and farmyard manure on soil water-nutrient status and sustainable productivity of maize (BH-540) grown on Sandy loam soil type of Adami Tulu area, mid rift valley of Oromia, Ethiopia. Twenty-seven experimental plots each on 3 m * 3 m area were conducted. The experimental design used RCBD with nine treatments vis-à-vis 3 and 5 tons ha-1of straw mulch, 3 and 5 tons ha-1of farmyard manure, the combination of these two levels of the treatments and a control without mulch and manure that were replicated three times. The results revealed that there was a highly significant difference (P<0.01) between the treatments regarding their effect on moisture conserving at FC and PWP, and yield and yield components of maize while most of the soil physical and chemical properties and the amount of moisture conserved through growth stages show significant differences (p<0.05). However, there was no significant difference in soil pH and EC at both soil depths. The moisture conserved through growth stages were more enhanced due to application of the combined form of straw mulch with manure by 20 cm interval up to 60 cm depth of the soil from germination to maturity stages. The results showed that application of straw mulch and farmyard manure could increase the soil moisture content by 16% to 28% in the three soil depth in relation to the control and enhanced the contents of N, P, K and OC while reducing bulk density up to 18% and 26% respectively at both depths. Also, the highest grain yield (11.837 tons ha-1 and 11.157 tons ha-1) were obtained in 5 tons ha-1 of straw mulch plus 5 tons ha-1 of farmyard manure and 5 tons ha-1 straw mulch plus 3 tons ha-1 farmyard manure treatments whereas the control resulted in the lowest grain yield (5.397 tons ha-1). These results indicated that retaining crop residue and application of farmyard manure in the field can be used as soil moisture conservation tool for sustainable improvement of maize production under the moisture stress and rainfall conditions of the study area.