| Solar radiation in Tibet ranks first in China, it is beneficial to the crop Photosynthesis. the dry matterpotential yield of winter wheat in Tibetan Plateau can reach32t/hm2,potential grain yield can reach14.4t/hm2,this is the1.45times of the other wheat production area. But in the real productionbecause of low soil fertility, a serious impact on the potential of the resources, become a major factorrestricting the production of wheat. The first Tibet soil survey was done in the1980s, and the soilsurvey shows the most Tibet soil lack N, P but potassium is very rich. So Tibet wheat fertilizer ratio isdesigned according to the soil survey, the ratio of N: P2O5: K2O is1:0.5:0.over the years comparedto the1980s soil nutrients have changed, and soil fertility has decreased. phosphorus and potassiumnutrient content is less than the lower surface of the soil, far from being able to meet the needs ofnormal growth, development of crops and pasture In the case of soil nutrient changes in, still usingthe previous design of the fertilization ratio, it is clear not to provide balanced nutrients for cropdemand. The thesis studied on soil nutrient of cultivated land in the agricultural region of "one rivertwo streams" of Tibet. Wheat fertilization research, fertilizer utilization, had been studied by plotexperiment setting up in two counties.Soil which were collected in8countries in the region of agrochemical analysis of one river twostreams" of Tibet agrochemical analysis shows nutrients are generally in a low level, low soil organicmatter content, with an average of18.58gkg-1. Compared with the second national soil surveynutrients grading standards,63.46%of the sampler is4,21.78%is3. Higher amount of total N, P andK in the soil, the average total nitrogen content is1.59g/Kg,60.94%of the sample total nitrogencontent reach the upper level,24.98%of the sample reach the middle level, and only14.09%of thetotal nitrogen content of the sample size belong to the lower levels. Average total phosphorus contentis7.7g/Kg, mainly concentrated in level2,3,4, slightly rich content; The average of the total K is20.49mg/kg, soil potassium content is higher.Available N,K is lower, despite the higher the total N, P and K in Tibet, The available nitrogencontent average of98.06g/kg, far below the national average,70.95%of the sample in the middle ofa low level. The average available phosphorus is12.6mg/kg, and82.36%of the sample in themiddle. The average of the available potassium is95.91mg of/Kg, compared with the secondnational soil survey standards only20.66%of the samples reaching third level,63%of the sampleslower than average. Tibet Soil available nitrogen relative lack of available phosphorus can still meetthe normal growth of crop needs, lack of effective potassium content, nitrogen will be the firstlimiting factor of crop yields, followed by potassium.Tibetan soil available nitrogen is deficiency;available phosphorus can still meet the normal growth of crop needs; lack of effective potassiumcontent. Nitrogen will be the first limiting factor for crop yields, followed by potassium.Field experiments were conducted in two counties in Tibet. The experimental are11treatments, they are OPT, OPT-N, OPT-P, OPT-K,1/2N,3/2N,2N,1/2K,3/2K,2N, and CK. Crop yields of the twotrail points is roughly the same trend, the highest yield of treatment2N, followed by3/2K, then OPTtreatment,-N-lower crop yields, after the no fertilizer control of CK, the yield of-P treatment justbelow the OPT treatment, has little effect on yield. Fertility factors which determining wheat yield,nitrogen, followed by potassium, phosphorus. |
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