The effect of previous crop, tillage and source of nitrogen on yield, quality and nodulation of second crop soybean

The objective of this study was to compare the effects of previous crop residue (wheat vs. lentil), tillage ( conventional tillage vs. no-tillage) and nitrogen source (rhizobial inoculant and fertilizer-N application) on yield, quality and nodulation of double-crop soybean. The field experiment was conducted at the experimental area of Dicle University Faculty of Agriculture, Field Crops Department, Diyarbakır in 2010. The experiment was laid out as split-split plot with three replications. According to results obtained from study, previous crop residue affected plant height, pod number per plant, first pod height, stem number and seed yield. Lentil crop residue treatment increased plant height, pod number per plant, stem number and seed yield, whereas decreased first pod height. Tillage treatment affected plant height, pod number per plant, first plant height, seed yield, nodule nitrogen concentration and nodule dry matter. Conventional tillage produced 20% greater seed yield than no-tillage treatment. Tillage didn?t affect nodulation, but previous crop residue x tillage x nitrogen source combination was affected nodule number per plant. Thus, wheat crop residue + no-tillage + rhizobium inoculation treatment had the highest nodul number per plant (78.5 no plant-1). There was significant effect of nitrogen source on plant height, pod number per plant, first pod height, stem number per plant, seed weight, seed yield, harvest index, oil content, nodule number, nodule nitrogen concentration and nodule dry matter. All characters examined generally increased with nitrogen source treatment compared to no nitrogen (control) treatment. An optimum soybean response in terms of seed yield was observed under lentil residue + conventional tillage and rhizobium inoculation treatment (321 kg da-1). This research demonstrates that applying rhizobium inoculation in no tillage system and lentil residue has the potential in increase soybean growth, seed yield and nodulation.KeyWords: Soybean, Previous crop, Tillage, Nitrogen, Rhizobium, Yield, Quality, Nodulation