Potassium Supplying Power of Soils in Heilongjiang Province and the Effect of Potassium Application on Resistance of Crops to Adverse Conditions

The total potassium(K)content of soils in Heilongjiang was relatively high in general and the available potassium content on soils was quite different for different soil types.The results of electro-ultra-filtration(EUF)analysis showed that the dark brown forest soils and the black soils in the northern part contained relatively high EUF-K,ranged from 12.5 to 15.7 mg per 100g soil.In the black soils in the southern part,the EUF-K ranged from 8 to 9mg per 100g soil.The albic and aeolian sandy soils contained low EUF-K,ranged from 3.2 to 4.8mg per 100g soil.Field experiment in 1982 indicated that potassium fertilizer in soils with medium or low EUF-K,increased soybean yield by 17%-34%,and obviously prevented the epidemic of meadow moth and soybean mosaic virus.Application of potassium fertilizer increased the protein and total sugar content of the plants,promoted transportation of nutrients,speeded up the growth of the plants,improved the resistance of crops to adverse conditions.Application of potassium fertilizer resulted in early maturity of crops(4-7 days earlier than cotrol),which had great significance for preventing crops from early frost damage.Hence,in order to keep nutrients balance in the soil and to increase soil fertility.potassium fertilizer or materials containing potassium must be applied to soils with medium and low EUF-K,such as black soils in the south part,ablic soils and aeolian sandy soils in Heilongjiang Province.

Potassium Supplying Power of Soils in Heilongjiang Province and the Effect of Potassium Application on Resistance of Crops to Adverse Conditions

The total potassium (K) content of soils in Heilongjiang was relatively high in general and the available potassium content in soils was quite different for different soil types. The results of electro - ultra- filtration (EUF) analysis showed that the dark brown forest soils and the black soils in the northern part contained relatively high EUF-K, ranged from 12.5 to 15.7 mg per 100 g soil. In the black soils in the southern part, the EUF-K ranged from 8 to 9 mg per 100 g soil. The albic and aeolian sandy soils contained low EUF-K, ranged from 3.2 to 4.8 mg per 100 g soil. Field experiment in 1982 indicated that potassium fertilizer in soils with medium or low EUF-K, increased soybean yield by 17%-34%, and obviously prevented the epidemic of meadow moth and soybean mosaic virus. Application of potassium fertilizer increased the protein and total sugar content of the plants, promoted transportation of nutrients, speeded up the growth of the plants, improved the resistance of crops to adverse conditions. Application of potassium fertilizer resulted in early maturity of crops (4 - 7 days earlier than control), which had great significance for preventing crops from early frost damage. Hence, in order to keep nutrients balance in the soil and to increase soil fertility, potassium fertilizer or materials containing potassium must be applied to soils with medium and low EUF- K, such as black soils in the south part, ablic soils and aeolian sandy soils in Heilongjiang province.