ISSN: 0041-3216 (Online), 0041-3216 (Print)
Volume 88 Number 4
Yield response of maize (Zea mays L.) to tied ridges and planting methods on Entisols and Vertisols of the eastern Ethiopian highlands. (165)
Low total rainfall and its uneven distribution during the crop season and low soil N and P levels are the principal factors limiting the production of maize in the eastern Ethiopian highlands. Thus, field experiments were conducted under rainfed conditions to study the effects of soil and water conservation treatments (tied ridges and planting methods) on the yield of improved maize variety EAH-75 on Entisols and Vertisols of the region. Five treatments (flat bed planting or control, planting on ridges of open end tied ridge, planting in furrows of open end tied ridge, planting on ridges of closed end tied ridge, and planting in furrows of closed end tied ridge) were laid down in a randomized complete block design with four replications. The experiment was conducted in two blocks (one without and another with N and P fertilizers) on both soil types to compare the effects of the treatments under natural and amended soil fertility levels. The yield of maize responded significantly (P <= 0.01) to tied ridges and planting methods both under fertilized and unfertilized conditions on both soils. However, the magnitude of the yield response and the relative efficiency of the tied ridges and planting methods varied with soil type, fertilization, and the total amount and distribution of rainfall during the cropping season. Regardless of the type of tied ridge used, furrow planting gave better grain yields than ridge planting. Specifically, open end tied ridge planting in furrows gave the highest yield across the four sets of experiments. Flat bed planting and open end planting on ridges produced the lowest grain yields on Entisols and Vertisols, respectively, both under fertilized and unfertilized conditions. Regardless of the soil fertility status, yield response to tied ridges compared with the traditional (flat bed) planting method was higher on Entisols than on Vertisols. Similarly, the grain yields accrued due to water conservation treatments were higher under fertilized than unfertilized conditions on both soils indicating the synergetic effects of soil water and NP nutrients on yield of the test crop. The study also revealed that yield responses were higher in seasons with low and poorly distributed rains and on shallow and coarse textured soil (Entisols) than in seasons with better rains and of the deeper and fine textured Vertisols. Thus, in areas of low and erratic rainfall such as the Alemaya areas of the eastern Ethiopian highlands, increasing rain fed crop yields largely depends on the use of improved soil and water conservation practices.
Keywords: Entisols, maize yield; np fertilizers; planting methods; tied ridge; vertisols