Fertilization techniques for High yield of Cotton

Fertilization is the most important and active link in cotton production. In order to obtain high yield of cotton, scientific fertilization must be done. The lint yield of Diandong and Sunwan villages in Tongshan County of Jiangsu Province has been more than 1500kg/hm2 for more than ten years. According to the investigation, the author's main experience on fertilization can be summarized into three words, namely "foot, early and complete".

1 "foot"

Adequate fertilizer is the basis of high yield. That is to say, target yield is determined according to production conditions and management level, and sufficient fertilizer amount is determined according to target yield. According to the experience of the high-yielding units mentioned above, in order to obtain lint yield index of 1500kg/hm2, the application rate of nitrogen fertilizer should not be lower than 375kg(referring to pure nitrogen) per hectare. According to the investigation of fertilizer application rate in Sunwan village, the average yield of lint cotton was 1 410 kg/hm2, the average nitrogen application rate was 301. 8 kg/hm2, and the average yield of lint cotton was 1 672. 5 kg/hm2, the average nitrogen application rate was 381kg/hm 2. The reason for applying sufficient fertilizer is that there is a large difference between the amount of fertilizer applied and the crop uptake. According to the investigation, the utilization rate of ammonium bicarbonate in that year was 44.5% in the mixed soil, 52.1% in the silted soil and only 25.2% in the sandy soil. Therefore, if the relationship between utilization rate and fertilizer application is not considered, the amount of fertilizer application is insufficient, which will restrict the increase of yield. However, if too much fertilizer is added, the economic cost of fertilizer must also be considered, so it cannot be blindly invested. According to the investigation in several high-yielding sites, within a certain range of fertilizer application, each increase of 0.5 kg urea can increase lint yield by 0.75-1kg, and increase output value by about 15 yuan, which is 10 times of the cost of fertilizer application. Therefore, to increase fertilizer application amount, the appropriate fertilizer application amount should be determined according to soil texture, production conditions, target yield, economic benefits of input and output. When lint yield is above 375kg/hm2, pure nitrogen application amount should be increased by 45-60kg in sandy soil and decreased by 30-45kg in clayey soil; when lint yield is above 1200kg/hm2, pure nitrogen application amount should be increased by 30-45kg in loamy soil and decreased by 30-45kg in clayey soil.

2 "Early"

With the increase of fertilizer amount, the fertilizer application method should be improved accordingly. The experience of high-yield unit is: appropriate advance fertilizer application time, that is, 40%-50% fertilizer is applied to the early stage of cotton growth, so as to ensure sufficient fertilizer to promote seedlings and early and stable bud stage. For example, in Sunwan Village, on the basis of applying 22,500 kg of soil miscellaneous fertilizer and 750kg of calcium superphosphate per hectare, topdressing was applied before wheat harvest (bud stage), and urea was applied 300kg per hectare, accounting for 36.4% of the total topdressing amount of urea in the whole year; Urea 300kg/ha was applied as top dressing fertilizer, accounting for 18.1% of the total amount of urea applied in the whole year. The fertilizer operation method mainly promotes early growth by applying fertilizer, not only takes into account the weak seedling in the early stage of wheat interplanting cotton, but also ensures sufficient fertilizer supply when a large number of bolls are formed in the middle and late stages, prevents fertilizer removal and premature aging, and ensures early growth and stable growth of cotton.

3 "All"

That is to say, nitrogen, phosphorus and potassium must be applied together in the structure of fertilizer elements. According to the soil nutrient content, carry out formula fertilization, change the unreasonable fertilization method of "heavy nitrogen and light phosphorus and potassium" in previous years. For example, many places in the past due to a single variety of fertilizer, potassium deficiency symptoms are obvious, resulting in a large area of leaf disease and red leaf stem blight. Even after a large amount of single nitrogen fertilizer application, the effect is still not obvious, which is directly related to the lack of potassium in soil. According to Mengzhuang test in 2004, cotton with 225kg potassium sulfate per hectare has 29.1 bolls per plant, 4.7 bolls more than cotton without potassium sulfate, 163.5 kg lint per hectare can be increased, yield increase reaches 14.6%, economic benefit increases by 2940 yuan, and net benefit after deducting cost increases by 1800 yuan; according to statistics of multi-point test in Zhangji Town in 2005, every 0.5 kg potassium fertilizer input in cotton field can increase lint by 0.73 kg on average. Therefore, it is an important measure that can not be ignored to increase potassium fertilizer application while applying sufficient nitrogen fertilizer.

4 Conclusion

Based on the experience of high yield fertilization in Zhangji Town of Tongshan County for many years, when lint yield is about 1500kg/hm2, the fertilizer application standard is: pure nitrogen 375-450kg, phosphorus pentoxide 150-180kg, potassium oxide 120-150kg per hectare, and soil miscellaneous fertilizer 15000 - 22500 kg. Such fertilizer application amount can basically meet the requirements of the above-mentioned yield indicators for nutrients.