Studies On Fertigation Application On Rice

In southern China area, the traditional fertilization on rice ismanually performedwith high labour cost, hard work and poor uniformity. In orderto improve uniformity and consistency of rice fertilization and reduce labor cost,pot and field fertigation experimentson early and late rice were conducted to investigate the solution flow stability and distribution uniformity. The effects of application, optimum application frequency,nutrient utilizationefficiency and and economic benefit offertigation on rice were analyzed or evaluated.The results obtained will provide some new ideas to the theoretical support for the extension of fertigation on rice in southern China.The main results were summarized as follows:1. Fertilizing by gravity automatic-flow fertilizer bucket, the tap switch open 30°at the beginning, and then 45°when the liquid level lower than 40 cm, could keep the water tap's flow relatively stable. The flow rate of pump suction fertilizer bucket maintained at 2L/min,better than gravity automatic-flow.2. The concentration of fertilizer was well-mixed with irrigation waterwhile using fan leaf at water inlet. The uniformity coefficient variation of rice fertigationof 1h, 4h and 16 h after application showed a decreasing tendency and had significant differences.The bigger area, the higher uniformity coefficient variation. The uniformity coefficient variation was reduced to 15%-10% after 16 hours to satisfy the uniformity of fertilizer no matter how big the field area.3. The fertigation improved rice effective panicle number, filled grains and yield. The yield of rice fertigation reached 7118kg/hm2, 730kg/hm2 higherthan broadcast application and 1392kg/hm2 higher than basal application,the yield increased by 11% and 24.3%. The rice fertigation decreased significantly labour cost, increased fertilizer use efficiency and economic benefit. The nitrogen use efficiencyincreased by 46.6% and 56.9% than broadcast application and basal application respectively. The potassium use efficiencyincreased by 23.4% and 75.0% than broadcast application and basal applicationrespectively. There was no significant difference of phosphorous use efficiency.4. The effective panicle number,1000-grain weight and yieldfirst increased and then decreased with the increase of fertigationfrequency. Topdressing of 3 times increased yield451.9kg/hm2 than broadcast application, and increase amplitude was7.8%; 1267kg/hm2 than basal application, and increase amplitude was25.6%. The highest profit was topdressing of3 times, with a net income of17615.7 Yuan/hm2, 4044yuan/hm2 more than basal application,1023yuan/hm2 higher than broadcast application.5. The fertigation was beneficial to improve the contents of nitrogen, phosphorus, and potassium of top 4th leaf during the heading stage of rice. It could effectively preventnutrient deficiency phenomenon during the late period.