Effect of nutrient management and moisture conservation practices on growth, yield and quality of snap bean (phaseolus vulgaris l.) in central Kenya

Abstract

Snap bean (Phaseolus vulgaris L.) is one of the major vegetables produced in Kenya mainly for the export market. Low soil fertility and limited moisture availability are the main factors hindering the realization of potential snap bean yields and high quality pods. On-farm trials were established at Kimbimbi in Kirinyaga South district and Kawanjara in Embu East district of Kenya to evaluate the effect of nutrient management options and moisture conservation practices on the growth, yield and quality of snap bean. In the first trial, the following nutrient management regimes were evaluated: control (no fertilizer), farmyard manure (5 t/ha) + minjingu phosphate rock (30 kg P/ha), farmyard manure (5 t/ha) + diammonium phosphate (26.9 kg N/ha and 30 kg P/ha), farm yard manure (5 t/ha) + calcium ammonium nitrate (60 kg N/ha), diammonium phosphate (43.2 kg N/ha and 48.2 kg P/ha) + calcium ammonium nitrate (46.8 kg N/ha) top dressed at 21 days after emergence, farmer practice [diammonium phosphate (30 kg N/ha and 33.5 kg P/ha ) + calcium ammonium nitrate (40 kg N/ha) top dressed at 21 days after emergence] and diammonium phosphate (43.2 kg N/ha and 48.2 kg P/ha ) + calcium ammonium nitrate (46.8 kg N/ha) top dressed at 21 days after emergence + wuxal foliar feed (pre-flowering). These treatments were laid out in a randomized complete block design and replicated three times. In the second trial, the following moisture conservation practices were evaluated: control (no ridges + no mulch), tied ridges, untied ridges, mulch + no ridges, mulch + tied ridges and mulch + untied ridges. Treatments were laid out in a randomized complete block design and replicated three times. Data collected in both trials included plant emergence, plant vigor, number of days to 50% flowering, number of days to 50% pod formation, insect pest infestation, disease infestation, plant stand at first harvest, number of pods per plant, pod length, extra fine pod yield, fine pod yield and total marketable pod yield. Data were subjected to analysis of variance and mean separation was done using the least significant difference test at p=0.05. xi Results of the first trial showed that fertilizer application significantly reduced the number of days to 50% pod formation in Mwea. Snap bean plants achieved 50% flowering and 50% pod formation earlier in Mwea than Embu by four and five days respectively. All the fertilizer treated plots significantly improved snap bean pod yield, yield components and quality compared to no-fertilizer control plots. In both sites, diammonium phosphate (DAP) + calcium ammonium nitrate (CAN) + foliar feed and DAP + CAN produced more vigorous snap bean plants, higher number of pods per plant and higher extra fine, fine and marketable pod yields than the farmer practice and all the other treatments. There were no significant differences between DAP + CAN + foliar feed and DAP + CAN in growth and yield parameters. The DAP + CAN + foliar feed treatment had a higher net profit than the farmer practice and other treatments. Results of the second trial showed that tied and untied ridges with or without mulch accelerated the time to 50% pod formation of snap bean plants in Embu. Use of ridges (tied or untied) with or without mulch led to increases in number of pods per snap bean plant, extra fine pod yield, fine pod yield and marketable pod yield. Mulch without ridges increased only the number of pods and fine pod yield in Mwea. The study has demonstrated that application of foliar feed in combination with DAP (43.2 kg N/ha and 48.2 kg P/ha) + CAN (46.8 kg N/ha) and use of mulch + untied ridges can enhance snap bean productivity and profitability under farmers’ fields in central Kenya.

Snap bean (Phaseolus vulgaris L.) is one of the major vegetables produced in Kenya mainly for the export market. Low soil fertility and limited moisture availability are the main factors hindering the realization of potential snap bean yields and high quality pods. On-farm trials were established at Kimbimbi in Kirinyaga South district and Kawanjara in Embu East district of Kenya to evaluate the effect of nutrient management options and moisture conservation practices on the growth, yield and quality of snap bean. In the first trial, the following nutrient management regimes were evaluated: control (no fertilizer), farmyard manure (5 t/ha) + minjingu phosphate rock (30 kg P/ha), farmyard manure (5 t/ha) + diammonium phosphate (26.9 kg N/ha and 30 kg P/ha), farm yard manure (5 t/ha) + calcium ammonium nitrate (60 kg N/ha), diammonium phosphate (43.2 kg N/ha and 48.2 kg P/ha) + calcium ammonium nitrate (46.8 kg N/ha) top dressed at 21 days after emergence, farmer practice [diammonium phosphate (30 kg N/ha and 33.5 kg P/ha ) + calcium ammonium nitrate (40 kg N/ha) top dressed at 21 days after emergence] and diammonium phosphate (43.2 kg N/ha and 48.2 kg P/ha ) + calcium ammonium nitrate (46.8 kg N/ha) top dressed at 21 days after emergence + wuxal foliar feed (pre-flowering). These treatments were laid out in a randomized complete block design and replicated three times. In the second trial, the following moisture conservation practices were evaluated: control (no ridges + no mulch), tied ridges, untied ridges, mulch + no ridges, mulch + tied ridges and mulch + untied ridges. Treatments were laid out in a randomized complete block design and replicated three times. Data collected in both trials included plant emergence, plant vigor, number of days to 50% flowering, number of days to 50% pod formation, insect pest infestation, disease infestation, plant stand at first harvest, number of pods per plant, pod length, extra fine pod yield, fine pod yield and total marketable pod yield. Data were subjected to analysis of variance and mean separation was done using the least significant difference test at p=0.05. xi Results of the first trial showed that fertilizer application significantly reduced the number of days to 50% pod formation in Mwea. Snap bean plants achieved 50% flowering and 50% pod formation earlier in Mwea than Embu by four and five days respectively. All the fertilizer treated plots significantly improved snap bean pod yield, yield components and quality compared to no-fertilizer control plots. In both sites, diammonium phosphate (DAP) + calcium ammonium nitrate (CAN) + foliar feed and DAP + CAN produced more vigorous snap bean plants, higher number of pods per plant and higher extra fine, fine and marketable pod yields than the farmer practice and all the other treatments. There were no significant differences between DAP + CAN + foliar feed and DAP + CAN in growth and yield parameters. The DAP + CAN + foliar feed treatment had a higher net profit than the farmer practice and other treatments. Results of the second trial showed that tied and untied ridges with or without mulch accelerated the time to 50% pod formation of snap bean plants in Embu. Use of ridges (tied or untied) with or without mulch led to increases in number of pods per snap bean plant, extra fine pod yield, fine pod yield and marketable pod yield. Mulch without ridges increased only the number of pods and fine pod yield in Mwea. The study has demonstrated that application of foliar feed in combination with DAP (43.2 kg N/ha and 48.2 kg P/ha) + CAN (46.8 kg N/ha) and use of mulch + untied ridges can enhance snap bean productivity and profitability under farmers’ fields in central Kenya.