Tie-ridge tillage for high altitude pulse production in northern ethiopia
Pulses including faba bean (Vicia faba L.), lentil (Lens culinaris Medic.), and field pea (Pisum sativum L.) are important components of the cropping systems of semiarid high-altitude northern Ethiopia. Yield potential is often constrained by severe water deficits during grain fill which might be alleviated by reducing runoff throughout the season using microbasin or tie-ridge tillage. Research was conducted to determine the effects of time of tie-ridge tillage and planting method on soil water availability and on the performance of these three pulse crops. The site was at 2740 m altitude on Torriorthent sandy loam or loamy sand soils. Eight treatments, including a 3 x 2 factorial of tillage x planting method, were evaluated in separate trials for each crop species in 2005 and 2006 with a randomized block design with three replications. Tie-ridge tillage improved soil water availability compared with the traditional practice of planting without ridges, and soil water was least depleted during the growing season with tie-ridge formation at 4 wk after planting (TR4WAP) when the first weeding was done. Grain yield and nodulation were also highest with TR4WAP, with mean grain yield increases of 79, 31, and 96% for faba bean, lentil, and field pea, respectively, compared with flat planting. Tie-ridging at other times typically resulted in increased grain yield compared with traditional flat planting if planted on the ridge, but decreased yield with in-furrow planting. Mean grain yield was 48, 23, and 35% with planting on the ridge compared with in-furrow if tie-ridging was done before planting for faba bean, lentil, and field pea, respectively. Soil water availability, however, was higher with in-furrow planting. Tie-ridging, or possibly reshaping earlier-formed tie-ridges, at the time of the first weeding after planting was most effective in improving pulse yield.