Department of Agronomy

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Browsing Department of Agronomy by browse.metadata.advisor "Andrade, M. I."

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    Effect of intercropping and phosphorous application on the growth and yield of sweetpotato, groundnut and soybean.
    (Stellenbosch : Stellenbosch University, 2017-03) Munda, Eliah; Pieterse, P. J.; Andrade, M. I.; Stellenbosch University. Faculty of AgriSciences. Dept. of Agronomy.
    ENGLISH ABSTRACT: Sweetpotato (Ipomoea Batatas (L) Lam) is among the most important root crops in Mozambique. However, the yield is lower than its genetic potential due to poor soil fertility and poor agronomic practices. Inorganic fertilizers that could contribute to yield increase are too costly hence they are not accessible. One of the feasible option is the use of intercropping with legumes to recapitalize soil fertility and improve yield. In this study the effect of intercropping sweetpotato with groundnut and soybean at three phosphorus (P) levels on soil chemical properties, sweetpotato, groundnut and soybean vegetative growth, yield and sweetpotato nutritional quality was investigated. The study was carried out at Umbeluzi Research Station during the 2013/14, 2014/15 and 2015/16 growing seasons. A factorial design in a split plot arrangement was used. The main plot treatments were; sole sweetpotato, sole groundnut, sole soybean, sweetpotato-groundnut, sweetpotato-soybean, sweetpotato- groundnut- soybean and groundnut- soybean intercropping. The subplot treatments were 0, 20 and 40 kg P ha-1 applied at planting. Sweetpotato- groundnut, sweetpotato- soybean and soybean- groundnut intercropping at 40 kg P ha-1 in the 2015/16 growing season had more soil total nitrogen (N) compared to sole sweetpotato (P=0.038). Soybean-groundnut intercropping at 0 kg P ha-1 in 2013/14 growing season had more Olsen P than sole sweetpotato in all growing seasons (P=0.023). Sweetpotato- groundnut and sweetpotato- soybean had 21 % and 25.3 % more soil CEC respectively than sole sweetpotato at 40 kg P ha-1. Sweetpotato- groundnut and sweetpotato- soybean intercropping at 40 kg P ha-1 had 42.9 % and 32.9 % more CEC than at 0 kg ha-1 respectively (P=0001). All treatments involving legumes in the mix had lower soil pH in 2014/15 and 2015/16 compared to 2013/14 growing seasons. Soybean- groundnut intercropping, sole groundnut and sole soybean had higher soil available potassium (K) compared to sole sweetpotato in 2015/16 growing season (P=0.001). Sweetpotato- soybean intercropping at 20 kg ha-1 had higher sweetpotato main stem length compared to sole sweetpotato. There was no significant difference in sweetpotato main stem length between 20 and 40 kg P ha-1 in the intercropping treatments (P>0.05). Sweetpotato- groundnut intercropping at 40 kg P ha-1 had higher fresh root mass plant -1 compared to sole sweetpotato crop in 2013/14 and 2014/15 growing seasons. Sweetpotato-groundnut- soybean-, sweetpotato-soybean and sweetpotato- groundnut intercropping at 0 and 40 kg P ha-1 had higher number of leaves plant-1 compared to sole sweetpotato. Sole sweetpotato had higher sweetpotato stem diameter compared to sweetpotato- soybean intercropping in 2013/14 and 2014/15 growing seasons. Sweetpotato- groundnut intercropping at 0 and 20 kg P ha-1 had 32.7 % and 58.5 % more total storage root yield compared to sole sweetpotato. (P=0.0001). There was no significant increase in total storage root yield between 20 kg P ha 1 and 40 kg P ha-1 for sweetpotato- groundnut, sweetpotato-soybean intercropping and sole sweetpotato (P>0.05). Highest sweetpotato partial land equivalent ratio of 1.6 was attained on sweetpotato- groundnut intercropping at 20 kg P ha-1. Total storage root yield increased by 33.6 % at 20 kg P ha-1 compared to 0 kg P ha-1. Sweetpotato- groundnut intercropping had 48.3 % more commercial root yield compared to sole sweetpotato at 20 kg P ha-1 (P=0.036). Sweetpotato- groundnut intercropping at 20 kg P ha-1 had 27. 4 % more number of storage roots plant-1 and higher harvest index compared to sole sweetpotato (P=0.001). Sweetpotato- soybean intercropping decreased number of storage roots plant-1 compared to sole sweetpotato in 2014/15 growing seasons (P=0.008). There was no significant difference in the number of storage roots plant-1 between sweetpotato- groundnut intercropping and sole sweetpotato cropping system (P>0.05). Sole sweetpotato at 20 kg P ha-1 had higher storage root diameter compared to sweetpotato-soybean intercropping (P=0.049). Sweetpotato- soybean intercropping had higher storage root length at 20 kg P ha-1 compared to 0 kg P ha-1 in 2013/14 and 2015/16 growing seasons (P=0.027). Total biomass at 20 kg ha-1 was higher than at 0 kg ha-1 in all treatments (P=0.0001). Sweetpotato- groundnut, sweetpotato-groundnut- soybean intercropping and sole groundnut had a significantly higher pod yield at 20 kg P ha-1 than at 0 kg P ha-1 (P=0.005). Groundnut-soybean intercropping had a significantly lower shelled groundnut yield than sweetpotato-groundnut at 20 kg P ha-1 (P=0.017). Percent dry matter content was higher in sole sweetpotato at 40 kg P ha-1 compared to any other treatments involving soybean. Sweetpotato- groundnut and sole sweetpotato at 20 and 40 kg P ha-1 had more percent glucose content in 2014/15 and 2015/16 compared to the 2013/14 growing seasons (P<0.05). Percent starch content at 40 kg P ha-1 was higher than at 0 kg P ha-1 in all growing seasons (P=0.0001). There was a significantly higher β-carotene content in the storage roots in 2015/16 than 2013/14 growing seasons. Sweetpotato- groundnut intercropping at 0 kg P ha-1 had a higher iron (Fe) content in the sweetpotato storage roots compared to any other treatment (P=0.000). Sweetpotato –legume intercropping had more zinc (Zn) content in the storage roots and Zn yield in sweetpotato in 2015/16 compared to 2013/14 growing seasons (P=0.033). Farmers with the same environmentl conditions as where this study was carried out are recommended to intercrop sweetpotato and groundnut at 20 kg P ha-1. Key words: intercropping, legumes, micronutrient deficiency, nutritional quality, sweetpotato.