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a The Key Lab. of Arid and Grassl. Agroecol., Lanzhou Univ., Ministry of Educ., Lanzhou, 730000, P.R. China
b Inst. of Soil and Fert., Gansu Acad. of Agric. Sci., Lanzhou 730070, P.R. China
c Agric. and Agri-Food Canada, Research Farm, P.O. Box 1240, Melfort, SK, Canada S0E 1A0
d Gansu Agric. Univ., Lanzhou 730070, P.R. China
e Inst. of Agric. Sci. of Zhangye Prefecture, Zhangye 734000, P.R. China
* Corresponding author (fmli{at}lzu.edu.cn).
Received for publication July 22, 2003.
A long-term (1982 to 2000) field experiment was conducted at Zhangye, Gansu, China, on a sandy clay loam (Typic Anthrosol) under wheat (Triticum aestivum L.)wheatcorn (Zea mays L.) rotation to determine the effects of N, P, and K chemical fertilizers and farmyard manure (M) on grain and straw yield, harvest index (HI), protein concentration, and N uptake in grain and straw and accumulation of nitrate N (NO3N) in the soil profile (0180 cm). The eight treatments from various combinations of fertilizers and M were check, N, NP, NPK, M, MN, MNP, and MNPK. Mean grain yield decreased in the order of MNPK
MNP > NPK > MN > NP > M > N > check (i.e., 8.01, 8.00, 7.51, 7.28, 7.00, 5.50, 4.89, and 3.43 Mg ha1, respectively). Yield response to applied N and P increased with time since yields in the check plots declined with time. Potassium fertilizer application provided no, slight, and dramatic increase in grain yield during the initial 6 yr, next 5 yr, and last 8 yr, respectively. Response of straw yield to fertilizers and M was similar to the grain yield. Mean HI increased with fertilizers in no-M treatments for both crops. Crude protein concentration and N uptake in grain and straw increased markedly with fertilizers, and M increased it further. Fertilizers (N, NP, and NPK) led to NO3N accumulation in most subsoil layers. Combined applications of fertilizers and M reduced soil NO3N accumulation in soil compared with fertilizers alone. In conclusion, the findings suggest that it is important to use balanced application of chemical fertilizers and M at proper rates in order to protect soil and underground water from potential NO3N pollution while also sustaining high crop production.
Abbreviations: HI, harvest index M, manure
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