Abstract:

Through the cotton drip irrigation of different N strategy and nitrogen nutrient and chlorophyll value related to drip irrigation precise N technology to provide the theory basis. In the field of 2 levels N were set up, 3 amount of nitrogen topdressing proportion, 6, and compares the differences, and the output SPAD-502 chlorophyll analyzer to measure changes SPAD value and soil alkali-hydro nitrogen analysis. Results showed that: 360 kg/hm2 nitrogen can obtain 3040.5 kg/hm2 production, but three chasing nitrogen proportion strategy on small differences 240 kg/hm2, nitrogen topdressing nitrogen under 3 percentage of yield significant influence strategy, 240 kg/hm2 of nitrogen SPAD lower overall value, 3 chasing nitrogen proportion strategy in the later stage SPAD value difference was not significant, but 360 kg/hm2 of nitrogen treatment in the later stage SPAD significant value. The law requiring fertilizer cotton yield ratio of SPAD recommended and soil alkali-hydro nitrogen correlation to the highest value 0.9367 R2 level. Enough, when adjusted for nitrogen topdressing nitrogen to high proportion of little impact. For nitrogen deficiency to yield, but there must be adjusted chasing nitrogen proportion of production space. Nitrogen fertilizer according to sufficient cotton and regularity of proportion of nitrogen recommendations, can delay the cotton is green, premature senility lost high.