摘要
Aims Crop nitrogen(N)and phosphorus(P)stoichiometry can influence food nutritive quality and many ecosystem processes.However,how and why N and P stoichiometry respond to long-term agricul-tural management practices(e.g.N fertilization and film mulching)are not clearly understood.Methods We collected maize tissues(leaf,stem,root and seed)and soil sam-ples from a temperate cropland under 30-year continuous N fer-tilization and plastic film mulching treatments,measured their C,N and P concentrations(the proportion(%)relative to the sample mass),and used structural equation models to uncover the re-sponding mechanisms for crop N and P contents(the total amount(g/m2)in crop biomass).Important Findings Long-term N fertilization increased N concentrations in all crop tissues but sharply decreased P concentrations in vegetative tis-sues(leaf,stem and root),thereby reducing their C/N ratio and increasing C/P and N/P ratios.The drop in P concentration in vegetative tissues was due to the dilution effect by biomass in-crement and the priority of P supply for seed production.In con-trast,film mulching decreased N concentration but increased P concentrations in most crop tissues,thereby increasing C/N ratio and reducing C/P and N/P ratios.Film mulching increased crop P content by increasing soil temperature and moisture;whereas,mulching showed little effect on crop N content,because a posi-tive effects of soil temperature may have canceled out a negative effect by soil moisture.This indicated a decoupling of P and N uptake by crops under film mulching.In conclusion,N fertiliza-tion and plastic film mulching showed opposite effects of on crop N and P stoichiometry.
基金
This work was supported by the National Science Foundation of China(41601307,41771328,41601247 and 41701330)
the National Key Research and Development Program of China(2016YFD0200304).
作者简介
Correspondence address:Fan Ding,College of Land and Environment,Shenyang Agricultural University,Shenyang 110086,China.These authors contributed equally to this article.Tel:+86-24-8848-7155,Fax:+86-24-8849-0886,E-mail:dingfan1985@syau.edu.cn;Correspondence address:Jingkuan Wang,College of Land and Environment,Shenyang Agricultural University,Shenyang 110086,China.Tel:+86-24-8848-7241,Fax:+86-24-8849-0886,E-mail:j-kwang@163.com;Shuangyi Li,These authors contributed equally to this article.
