Effect of sulphate-potassium magnesium on growth and nutrient absorption of peanut in poor-K acid soil

A pot experiment was carried out to determine the effects of sulphate-potassium magnesium fertilization level on the growth and nutrient absorption of peanut in poor-K acid sandy soil. The results show an improvement in economic and total biological yields of peanuts, which subsequently drop with increasing sulphate-potassium magnesium application levels in the soil. Peanut yield is highest at 513 mg sulphate-potassium magnesium per kg of soil (corresponding to 0.12 g K2O, 0.028 g Mg and 0.09 g S per kg soil), with economic and total biological yields improve by 20.2% and 32.2% respectively over CK. With increasing sulphate-potassium magnesium application level, the respective absorptions of K, Mg and S variously improve. The absorptions of K and S steadily improve, while the absorption of Mg initially increases and subsequently drops. Correlative interactive effects of absorption of K and Mg are positive. Peanut quality increases with increasing sulphate-potassium magnesium application level, and coarse protein and fat contents of nutlet variously improve over CK. The content of coarse protein steadily increases, whereas that of coarse fat steadily drops. This suggests that in the acid sandy soil with low level of K, middle level of Mg, and potential S stress, fertilizing peanuts with sulphate-potassium magnesium leads to a significant positive correlation between K and Mg absorption. However, the correlation between K and S absorption is not so obvious.