Pyrethrum Marc Rates and Intra-row Spacing Influence on Selected Soil Chemical Parameters and Yield of Bush Bean (Phaseolus Vulgaris L.) Grown on Andosol Under Rainfed Conditions

Abstract

Bush bean is an important pulse crop which enriches Rwandan diet and source of cash. This staple crop is widely grown in Rwanda and however, the improper spacing and inadequate application rates of organic inputs results in low yields. The purpose of study was to evaluate the effect of intra-row-spacing and pymarc application rate on selected soil chemical parameters and bush bean (Phaseolus Vulgaris L) yield on andosol under rainfed conditions. The experiment included 5 pymarc rates with four replications in a randomized complete block design : P0(No fertilizer), P1(250 kg ha^-1 of NPK), P2(10 tons ha^-1of pymarc + 250 Kg ha^-1 of NPK), P3(15 tons ha^-1 of pymarc + 250 Kg ha^-1 of NPK) and P4(20 tons ha^-1 of pymarc + 250 Kg ha^-1 of NPK) and 3 spacing levels: S1(40 cm x 15 cm), S2(40 cm x 20 cm) and S3(40 cm x 30 cm). The results indicated that a significant difference was found out between treatments and their interactions except pH (p<0.05). Regarding pymarc treatments, P4 contained greater amounts of organic C(5.30 %), total N(0.30 %), available P(56.70 ppm), available K(81.30 mg/dm³), exchangeable Ca(12.61 Cmol/Kg) and Mg(5.0 Cmol/kg) at harvesting compared to P0 and P1. According to plant spacing, S3 held higher amounts of OC(4.85 %), av. P(55.15 %), av. K(60.94 mg/dm³), exch. Ca(11.0 Cmol/Kg) and exch. Mg(3.6 Cmol/Kg) than S1. There was interaction effect of pymarc and spacing on measured soil chemical properties except soil pH. The correlation analysis between nutrients was positive, highly significant (p<0.01) and varied from moderate to strong (0.4<r<0.7 and r>0.7) except pH. The treatment with high bush bean yield was P2S1 with 3.03 tons ha^-1 and therefore it can be recommended to bush bean farmers of volcanic highland region.