[Nitrate leaching characteristics of wheat-corn rotation farmland in Guanzhong area of Shaanxi].
By using in situ leaching device, a field experiment was conducted to study the effects of nitrogen fertilization rate and straw mulching on the nitrate leaching at 90 cm soil depth, nitrate accumulation in soil profile (0-100 cm), crop yield, and nitrogen balance of wheat-corn rotation farmland in Guanzhong area of Shaanxi. Six treatments were installed, i. e., no fertilization (N1, 0 kg x hm(-2) x a(-1)), conventional fertilization (N2, 471 kg x hm(-2) x a(-1)), recommended fertilization (N3, 330 kg x hm(-2) x a(-1)), reduced N application (N4, 165 kg x hm(-2) x a(-1)), increased N application (N5, 495 kg x hm(-2) x a(-1)), and recommended fertilization plus straw mulching (N3 + S). The nitrate leaching loss was increased with increasing N fertilization rate. Excessive N fertilization and straw mulching could easily cause nitrate leaching. In treatment N3 + S, the annual NO3(-) -N loss at 90 cm soil depth was the greatest (22.32 kg N x hm(-2)), and the NO3(-) -N loss from N fertilization was 16.44 kg N x hm(-2) x a(-1), being 158.9% higher than that in treatment N3. Nitrate mainly accumulated in 20-60 cm soil layer. When the N application rate was 330 kg N x hm(-2) x a(-1), straw mulching had less effect on the NO3(-) -N distribution in soil profile. No significant difference was observed in the crop yield among the treatments, but reduced N application (N4) tended to decrease the yield. Under our experimental condition, a fertilization rate of 150 kg N x hm(-2) x a(-1) for wheat and 180 kg N x hm(-2) x a(-1) for maize could ensure the crop production and reduce the soil nitrate leaching and accumulation.
Yin
Xiao-Fang
XF
College of Resources and Environmental Sciences, Northwest A & F University, Yangling 712100, Shaanxi, China. fangjj105@163.com
Tong
Yan-An
YA
Zhang
Shu-Lan
SL
Zeng
Yan-Juan
YJ
Gao
Peng-Cheng
PC
Zhou
Jun
J
Yang
Xian-Long
XL
D000383:Agriculture / Q000379:methods*; D005308:Fertilizers; D009566:Nitrates / Q000032:analysis*; D009584:Nitrogen / Q000032:analysis / Q000494:pharmacology*; D014908:Triticum / Q000254:growth & development*; D003313:Zea mays / Q000254:growth & development*
D005308:Fertilizers; D009566:Nitrates; D009584:Nitrogen