Effect of Phosphorus Application on the Growth and Yield of Sweet Potatoes in Embu West Sub-County

Abstract

Sweet potato is among the drought-resistant crops that take a short period to mature. Therefore, sweet potato plays a significant role in food security in Kenya because of its high degree of flexibility. Embu West Sub County's main economic activity is agriculture, which is the economic pillar of Embu County. Most farmers at the grassroots level have not been able to access proper fertilization on their farms because of a lack of adequate and authentic knowledge. This study focused on the sweet potato fertilization regime, especially the application of phosphorous. The of study's objectives were; to determine the yield potential of three sweet potato varieties, to determine the effect of P levels on growth and yield of sweet potatoes and to evaluate the effect of interaction between the sweet potato varieties and P levels. The study was carried out in Embu west at KARLO EMBU farm in two different seasons season 1 during the long rains (April to September2016) while season 2 was carried out during the short rains (November 2016 to April 2017). Land was cleared, dug and harrowed to fine tilth manually. Using RCBD, land was divided into three blocks. Each block had twelve plots each measuring three meters by three meters. Each plot received a combination of two treatments that is sweet potato variety and a specific level of P. Treatments was randomly assigned on the experimental units. The sweet potato varieties used were SPK004(V1), Kenspot 3(V2) and Kenspot 4(V3).The P fertilizer levels used were 0 kg/ha(P1), 25 kg/ha(P2), 50 kg/ha(P3), and 75 kg/ha(P4). Data on specific growth and yield parameters was collected throughout the study period, the collected data was summarized using excel. SPSS version 23 was used for ANOVA, at α=0.05.For treatment means that were significantly different LSD as Post hoc test was used to separate them. The study showed significant yield potential difference in all yield parameters among the three sweet potato varieties with Kenspot 4 being the highest producer of both marketable tubers yield and biomass above the ground. The study showed that the amount of P applied significantly affect growth and yield of sweet potatoes with a P level of 50 kg/ha being the recommended rate. According to this study, interaction between the variety of sweet potatoes and the P levels applied had no significant influence on the growth and yield of sweet potato