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Impact of soil acidity on groundnut productivity in Mpumalanga and KwaZulu - Natal Province

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dc.contributor.advisor Zharare, G.E
dc.contributor.advisor Zobolo, A.M
dc.contributor.author Vilane, Nkiza Michael
dc.date.accessioned 2017-09-20T10:59:52Z
dc.date.available 2017-09-20T10:59:52Z
dc.date.issued 2016
dc.identifier.uri http://hdl.handle.net/10530/1616
dc.description A thesis submitted to the Faculty of Science and Agriculture in partial fulfillment of the requirements for the Degree of MSc Agriculture (Agronomy) in the Department of Agriculture at the University of Zululand, 2016 en_US
dc.description.abstract Groundnut [Arachis hypogaea L.] is grown on sandy or sandy loam soil by the smallholders in the lowveld region of Mpumalanga and the Northern coast of KwaZulu-Natal. These soils are highly susceptible to leaching, which leads to acid-soil infertility. The goal of the current study was to examine the fertility status of the soils where groundnuts are grown traditionally in Mpumalanga and KwaZulu-Natal in relation to groundnut production with a special emphasis on acid soil infertility factors which include low pH, nutrient deficiencies and toxic levels of manganese [Mn]. First, a soil survey was conducted in the two areas to assess the fertility status of the soils, in which chemical analyses were done for the top 10 cm, 10-40 cm and 40-60 cm soil depth layer. This was followed by two sets of field experiments that examined the performance of groundnut in these soils with and without lime application. The first experiment [Experiment 1] compared the yield performance of 16 groundnut Varieties in very acid soils at Manguzi in the Northern KwaZulu-Natal and Lowveld College of Agriculture farm near Nelspruit in Mpumalanga lowveld during the 2008-2009 season. In the second experiment [Experiment 2], six varieties selected from Experiment 1 were tested in acid soils during the 2009-2010 season to determine their yield responses to three rates [0, 750 and 1500 kg/ha] of calcitic and dolomitic limes at the Lowveld College of Agriculture farm and calcitic lime at Manguzi. The soils were generally acidic at both sites and low in mineral nutrients. The soils at Nelspruit were particularly deficient in K [22 to 107 mg/kg], and low in Ca [136 to 445 mg/kg] and Mg [ 28 to 96.6 mg/kg] and differed in this respect from the soils at Manguzi which had higher K [126 to 200 mg/kg], Ca [396 to 1277 mg/kg] and Mg [111 to 166 mg/kg] concentrations whose ranges were substantially above the ranges [40 to 88 mg/kg for K, 100 to 250 mg/kg for Ca and 10 to 30 mg/kg for Mg] considered adequate for groundnut. The soils in Manguzi and Nelspruit were also sufficient in Zn and Mn as the ranges of these nutrients were between 0.4 to 26.1 mg/kg for Zn and 3 to 24 mg/kg for Mn, which were within the ranges [0.5 to 1.0 mg/kg for Zn and 3 to 7 mg/kg for Mn] considered adequate for groundnut. However, at Lowveld College of Agriculture farm these nutrients were higher than at Manguzi. The sites sampled differed in pH, Ca, Mg, K, P, Fe, Zn, and Mn distribution down the soil profile, but there was no definite trend in the distribution patterns of the nutrients. The soil pH was highly correlated with Mg at Nelspruit, but at Manguzi, the pH was most correlated with Ca in the 10 to 40 cm soil layer. In Experiment 1, Anel [≥ 1709 kg/ha], ICGV 95714 [1457 kg/ha] and Inkanyezi [1456 kg/ha] yielded well in terms of grain yield under low soil pH conditions in the Mpumalanga lowveld, but at Manguzi the varieties that had outstanding performance under low soil pH were Inkanyezi, Mwenje, ICGV 99529 and RGV-784 which yielded 2358 kg/ha, 1664 kg/ha, 1599 kg/ha and 1444 kg/ha of grain yield, respectively. The application of lime selectively improved the yields of the varieties. Furthermore, the response of the varieties (Anel, ICGV 95714 and Inkanyezi) to lime application at Lowveld College differed from that at Manguzi. The ability of the test varieties to tolerate soil acidity differed. Varieties JL -24, Inkanyezi, RGV -784 and Rambo were highly sensitive to soil acidity, since their grain yields increased substantially when the lime rates were increased at the Lowveld College of Agriculture farm and at Manguzi. By contrast, varieties Kwarts and ICGV 90071 were insensitive to liming as their grain yields did not respond to liming at the Lowveld College of Agriculture farm. Also, Rambo was insensitive to liming at Manguzi. The variety Kwarts was found to be better suited for acidic soil conditions at Lowveld College of Agriculture farm whereas at Manguzi, Rambo was found suitable for acidic conditions. Groundnut varieties JL-24, RGV-784 and Inkanyezi performed best under half and the recommended lime rates at Lowveld College of Agriculture farm. At Manguzi, Inkanyezi performed outstandingly under half (750 kg/ha) and recommended (1500 kg/ha) lime rate. Of the two limes sources tested at Lowveld College of Agriculture farm, calcitic lime was found suitable as the mean of grain yields were higher in half and recommended lime rates compared to the dolomitic lime. It was noted that in some cases, there was in fact a reduction of yield in some varieties in lime-amended soils. This was most conspicuous for varieties Kwarts at Lowveld College Agriculture farm and Rambo at Manguzi. This could have been caused by interference of Ca and Mg on the uptake of micronutrients such as e.g. Zn or Mn. en_US
dc.description.sponsorship National Research Foundation en_US
dc.publisher University of Zululand en_US
dc.title Impact of soil acidity on groundnut productivity in Mpumalanga and KwaZulu - Natal Province en_US
dc.type Thesis en_US

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