灌溉施肥对棉花产量及用水效率影响的研究

灌溉与施肥是影响棉花产量的两个主要因素。田间试验表明：（1）干旱年份增加灌水量可明显地提高棉花水分生产效率,2008年灌水2次的水分生产效率达到最大值0.289kg/m3;（2）在本项目试验田的肥力水平条件下增加施肥量的增产潜力不大,但减少施肥量会显著地降低产量;（3）在施肥和灌水次数相同的条件下,灌水时间不同在一定程度上影响作物蒸发蒸腾量在生育期内的分配,对蒸发蒸腾量的总量影响不大,但对产量影响较大。在同样灌水量和施肥条件下,同一年度内采用合理的灌水时间可增产15.9%（2006年）~21.0%（2008年）。表明灌溉预报具有较大的增产潜力;（4）棉花累计蒸发蒸腾量随时间的变化过程线在生长后期趋于平缓,符合S形曲线（生长曲线）,主要原因是棉花后期大气蒸发力明显地减小。棉花的蒸发蒸腾量主要发生在60d（播种日算起）之后,其蒸发蒸腾量要占到全生育期蒸发蒸腾量的80%以上。

Study on impacts of irrigation and fertilization on cotton yield and water use efficiency

Irrigation and fertilizat ion are the two main factors affecting cotton yield. Field experiments conducted by authors reveal the following results. ( 1) Increase in irrigation water quant ity in dry years can significantly improve cotton water productivity. In 2008, irrigation water production efficiency reached its maximum value of 0.289kg/m3 . ( 2) Potent ial yield growth due to increasing fertilization is rather small under the current fert ilization level in pilot fields, however, a reduction of fertilizer would lead to a significantly fall in yields. ( 3) With the same times of fertilizing and irrigating, irrigation at different time would result in a different distribut ion of crop evapotranspirat ion in growth period, which would make a slight impact on the total amount of evapotranspiration, but a great impact on yields. A timely irrigation forecast will contribute to a great potential of yield growth. ( 4) The accumulat ive curve of cotton evapotranspiration, changing with time in line with S-shaped curve (growth curve) , goes gently in the late growth period because of a remarkable recession of atmosphere evaporation. Evapotranspiration of cotton mainly occur during the first 60 days ( since the sowing date) , taking up more than 80% of the total value in the whole growth period.