Effect of potassium rates and sources on the growth performance and on chloride accumulation of maize in two different textured soils of Haripur, Hazara Division

The present study was based on the hypothesis that muriate of potash is a cheaper and rich source of potassium, but adversely affects the crops yield due to high Cl content. For this reason both column and field experiments were conducted to study the effect of potassium rates and sources on the availability of Cl, SO4 and K to maize crop growing on Haripur and Ghazi soils during 2004. In column experiment two sources of potassium i.e. muriate of potash was applied @ 0, 50, 100 and 150 kg per ha and sulphate of potash was applied to one column @ 150 kg per ha in each column of the two sets along with a basal dose of N 120 and P2O5 80 kg per ha. Chloride content of both sets of columns increased with each increment of muriate of potash, but the soil Cl accumulation occurred in the lower part of each column i.e. 30-60 cm. However, some replacing effect of SO4 on original Cl level was also observed. Moreover, the effect of muriate and sulphate of potash on soil Cl accumulation in soil profile and comparison of both potassium sources in terms of maize yield were also studied in the field at two locations. Potassium was applied @ 0, 50, 100 and 150 kg K2O per ha as muriate and sulphate of potash along with a basal dose of N 120 and P2O5 80 kg per ha. Grain yield of maize crop was significantly increased with both sources of potassium fertilizers over NP alone treated plots (control). Further more results revealed that the grain nutrient ratio (GNR) and value cost ratio (VCR) of the both locations were found almost equal, indicated that Cl ions from muriate of potash had no adverse or toxic effects on grain yield of maize crop. Tissue Cl, S and K contents at silking stage were significantly increased with the addition of their respective fertilizer sources, but no harmful effect of Cl was observed on the growth of maize crop. Moreover, results indicated significantly positive and linear correlations between Cl leaching and applied MOP in both test soils at crop harvest, because present studies suggested that Cl ion was highly soluble and mobile in soils during crop growth, which leached down from the root zone with irrigation water. The overall results indicated that the effect of K in terms of sulphate and muriate of potash on the growth performance of maize crop was found statistically at par, because Cl from the muriate of potash leaches down the profile with irrigation water and does not accumulates in the root zone and therefore no toxic/adverse effects were observed on maize crop under the conditions of the experiments.