不同施肥处理对白菜的物质积累与养分吸收的影响

研究了在洞庭湖平原的冲积性菜园土条件下,不同施肥结构对白菜生育期间的物质积累与白菜对N,P,K养分的吸收规律以及土壤有效N,P,K养分的动态变化.结果表明,不同处理白菜的产量相差较大,各施肥处理比不施肥对照平均增产达33.1%,但各施肥处理之间产量差异不显著.白菜对N,P,K养分的吸收都是在移栽30 d以后的生长中、后期,与其地上部生物产量的积累规律一致.专用肥处理和有机无机肥配施处理明显促进白菜对N,P,K养分的吸收.从而提高白菜对肥料养分的利用率.当地习惯施肥处理的N,P施用量明显过大,浪费肥料,也对当地水体及环境造成污染.其施K量明显低于白菜一季的总吸钾量,既影响白菜产量和品质,也造成土壤K素的耗竭.根据不施肥对照和4个平衡施肥处理白菜地上部分的养分吸收总量结果,以白菜对肥料N,P,K的当季利用率分别为40%,25%和60%计算,供试土壤条件下白菜一季所需N,P_2O_3,K_2O的施用量分别为195.25 kg/hm~2,145.60 kg/hm~2,228.53 kg/hm~2.其N:P_2O_5: K_2O值为1:0.75-1.17.

Effects of Different Fertilizations on Substance Accumulation and Nutrient Uptakes of Chinese Cabbage under Field Conditions

A fieid plot experiment was carried out to study dynamic change of biomass accumulation and N, P and K nutrient uptake of Chinese cabbage, and soil nutrient content at different growth stages as affected by various fertilizations under the alluvial vegetable soil in Dongting lake plain. The results showed that both combined application of organic and inorganic fertilizer and pure inorganic chemical fertilizer application increased the aboveground biological output of the vegetable crop, but the growth rate of Chinese cabbage under the mixed application of organic and inorganic fertilizers was higher than that under pure inorganic chemical fertilizer application. About 1/2 biomass accumulation of Chinese cabbage mainly appears in the middle vigorous growth period from the 30th to 50th days after transplanting. The laws of N, P and K absorption of Chinese cabbage was similar with the laws of aboveground biological accumulation of Chinese cabbage. The ratio of N : P_2O_5 : K_2O absorbed by Chinese cabbage treated with 4 balanced fertilizations was 1 :0. 45 : 0. 95. It demonstrated that Chinese cabbage demanded much more N and K than P. More than 50% nutrient was absorbed in the middle vigorous growth period. According to the nutient uptake of Chinese cabbage under CK and 4 balanced fertilizations treatments, the application rates of N, P_2O_5, K_2O for Chinese cabbage should be 195. 25 kg/hm~2,145. 60 kg/hm~2 and 228. 53 kg/hm2,respectively, giving the ratio of N : P_2O_5 : K_2O=1 : 0. 75: 1. 17 provided that the apparent recovery of Chinese cabbage for N, P and K of fertilizers is 40%,25% and 60% .respectively.