Critical Magnesium Levels in Soil and Potato (Solanum tuberosum) Plants Grown on Lateritic Red Soils
摘要
Critical level of nutrients in soil and plants indicates the threshold limits of the nutrient that distinguish its deficiency from sufficiency which avoids yield loss and advocates optimal fertilizer application. The study aims to fix a critical limit for magnesium (Mg) in soils and plants by conducting field experiments to establish the critical level of magnesium in soil and potato plants on red lateritic acid soils having low, medium, and high Mg status. Graded levels of magnesium as magnesium sulphate (MgSO4) were applied at 0, 20, 40, 60, 80 and 100 kg ha−1 basally at the time of planting using potato variety Kufri Jyothi as the test crop. The critical magnesium level in soil and plants established using Cate and Nelson graphical and statistical methods was 42 mg kg−1 for soils and 0.27% Mg in potato plants at the flowering stage in both the methods to advise fertilizer Mg recommendations. The results also revealed a linear and significant response of the potato crop to increasing levels of Mg fertilization which varied with native soil Mg status, and a higher response was registered in low Mg soils. Basal soil application of recommended NPK + 60 kg MgSO4 ha−1 was found optimal and economical for achieving higher tuber yield in potato on red laterite soils.