Effects Of N Application On Crop Nutrient Uptake And Soil NO-3~--N Content In Maize And Potato Intercropping

Maize and potato intercropping is one of the important planting patterns in southwest China, which has significant yield advantages. This intercropping system is widely distributed in the central region, northeast and northwest of Yunnan province. The previous research of maize and potato intercropping focused on biomass and yield, the field configuration, light utilization, plant diseases and insect pests, interspecific relationship and so on. The research of intercropping nutrient absorption and environmental emissions is of great significance. In this study, field experiment was carried out to study the effects of 4 N levels(maize N0(0 kg/ha), N1(125 kg/ha), N2(250 kg/ha), N3(375 kg/ha), potato N0(0 kg/ha), N1(62.5 kg/ha), N2(125 kg/ha), N3(187.5 kg/ha))on the yield, crop nutrient absorption and distribution in grain, stem and leaf and root of crops and soil NO3--N content in maize and potato intercropping. The main results are as follows:(1) Maize and potato intercropping has yield advantages. The Land Equivalent Ratio(LER) of 4 N levels(from N0 to N3) was 1.46、1.20、1.04、0.92, respectively. The intercropping yield advantage was decreased with increasing of nitrogen level and there was no intercropping yield advantage at N3 level(LER<1). The yield advantage of intercropping was mainly from the maize. Compared to monocropping, the intercropping maize had 21.98% to 70.63% yield advantages. Maize was the dominant species and potato was the subordinated species in the intercropping.(2)Intercropping improved maize N, P, K absorption. The intercropping maize N, P, and K absorption of grain, stem and leaf, root were higher than monocropped, respectively. The intercropping potato N, P, K absorption was higher than monocropped in N0 and N1, and less than monocropped in N2 and N3. N application improved N, P, K absorption of intercropping maize and potato. The maize intercropping advantages of N, P, K absorption was decreased with increasing of nitrogen level. The effect of intercropping and nitrogen fertilizer on N, P, K distribution proportion in organs of maize and potato was not significant.(3) The effect of 3 cropping patterns on The NO3--N content in the topsoil(0-20cm) was not significant in each period except seedling period. In maize//potato systems, the NO3--N content in topsoil at different growth stages showed certain regularity change, and the NO3--N content increased with increasing of nitrogen level. The NO3--N content in the topsoil of seedling stage was highest in the whole growth period. It was decreased from seedling stage to huge bellbottom period, and it showed “M”(double peak) curve in the later periods, and it reached a minimum after the harvest. After the harvest, the NO3--N content in soil profile(0-75cm) was presented as maize monocropping>potato monocropping>intercropping. The NO3--N content in soil profile increased with increasing of nitrogen level of 3 cropping patterns.