Study The Effects Of Different Forms And Different Concentrations Of Potassium In Rice- Wheat Rotation System

Rice and wheat are two important food crops in China, and the stable production of rice and wheat is the guarantee of national food security. Potassium, one of the main necessary nutrients of crop, which is involved in many important biochemical processes of plant and could siginificantly promote growth and increase resistance of rice and wheat. However, the self-supplying rate of potassium fertilizer is very low in China and its import dependence rate was 70%, the demand and import growth of potassium fertilizer lead to the international prices increasing of potassium fertilizer. The increasing price of potassium fertilizer has become one main reason of agricultural production cost growth and an important problem that limit the sustainable and healthy development of agriculture. Water-soluble potassium fertilizer resources are quite poor in our country and large quantities of potassium fertilizer were imported from foreign country. However, the reserve of citrate acid-soluble potassium mineral was widely existed. So it is very important to explore citrate acid-soluble potassium fertilizer to solve the problem of potassium resources lacking in our country.To clarify the effects of citrate acid-soluble potassium fertilizer on rice-wheat rotation system, two parts of different amount of citrate acid-soluble potassium fertilizer and different ratio of citrate acid-soluble potassium fertilizer to water-soluble potassium fertilizer were conducted in pot experiment. The roles of citrate acid-soluble potassium fertilizer on the current season effect of wheat and the later season effect of rice were investigated. Different potassium fertilizer application content were setted as main treatment and wheat straw application was deputy treatment, a field experiment was conducted to clarify the potassium demand regularity of rice and wheat as well as the influence of wheat straw application to the rice-wheat rotation system. The pot experiment results obtained were as follows:1.the wheat and rice yield, biomass and potassium accumulation were significantly enhanced as the citrate acid-soluble potassium fertilizer application amount increased. therefore, application of a high level of potassium can cause a luxury absorbed. When applying the same amount of water-soluble g·kg-1 (WP100%) and citrate acid-soluble potassium fertilizer (CP1), the effect of WP100% was better than CP) in the wheat season, whereas the CP1 was better in the rice season. The application of 0.150-0.225 g·kg-1 citrate acid-soluble potassium fertilizer were needed to replace the water-soluble potassium fertilizer.2.when application equal amount of potassium fertilizer, different ratio of citrate acid-soluble potassium fertilizer to water-soluble potassium fertilizer could increase the crop biomass, crop yield, potassium content, potassium accumulation, the potassium utilization efficiency and soil available K content, as compared to control. The best ratio of citrate acid-soluble potassium fertilizer to water-soluble potassium fertilizer was 1:1(WP50%). In conclusion, citrate acid-soluble potassium fertilizer could replace or partly replace the water-soluble potassium fertilizer. The field experiment results obtained were as follows:1. The yield of rice and wheat showed a downward trend after rising with the increase of potassium application amount, potassium fertilizer affect the yield of rice mainly through affecting the panicle, grains per panicle and seed setting rate. The fertiilize effect on wheat yield was through influencing 1000-grain weight of wheat. The treatment of 225g·kg-1 potassium fertilization on rice and wheat showed significantly luxury absorption of patassium during their growth period and had no significant effect on crop yield. The treatment of 400g·kg-1 potassium fertilization have inhibitory effect on rice yield.2.The biomass of rice and wheat were constantly increased their growth period, while potassium accumulation amount showed a decreasing trend after a increasing, which was due to the potassium loss for the rice and wheat aging and secrete potassium effect in their late growth period3 Wheat straw application had adverse effect on the early stage of rice growth, but as the fermentation and decomposition of straw, wheat straw application was helpful to the vegetative and reproductive growth of rice.