Long-Term Fertilizer and Water Availability Effects on Cereal Yield and Soil Chemical Properties in Northwest China
2005
Fan, Tinglu | Stewart, B. A. | Payne, William A. | Yong, Wang | Luo, Junjie | Gao, Yufeng
Wheat (Triticum aestivum L.) and corn (Zea mays L.) rotation is important for the region's food security in Northwest China. Grain yield and water-use efficiency (WUE: grain yield/estimated evapotranspiration [ET]) trends, and changes in soil properties during a 24-yr rainfed fertilization experiment in Pingliang, Gansu, China, were recorded. Mean wheat yields for the 16 yr ranged from 1.29 Mg ha⁻¹ for the unfertilized plots (CK) to 4.71 Mg ha⁻¹ for the plots that received manure (M) annually with inorganic N and P fertilizers (MNP). Corn yields for the 6 yr averaged 2.29 and 5.61 Mg ha⁻¹ in the same treatments. Yields and WUEs declined with years except for the CK and MNP treatments for wheat. Wheat yields for the N and M treatments declined about 80 kg ha⁻¹ yr⁻¹, compared with about 60 kg ha⁻¹ yr⁻¹ for the NP treatment and the N plus straw treatment receiving P every second year (SNP). Likewise, the corn yields and WUEs declined significantly for all treatments. Grain yield-ET relationships were linear with slopes ranging from 0.51 to 1.27 kg ha⁻¹ m⁻³ for wheat and 1.15 to 2.03 kg ha⁻¹m⁻³ for corn. Soil organic C (SOC), total N (TN), and total P (TP) gradually increased with time except the CK, in which TN and TP remained unchanged but SOC and available P (AP) decreased. Soil AP decreased in the N treatment. Soil available K declined rapidly without straw or manure additions. The greatest SOC increases of about 160 mg kg⁻¹ yr⁻¹ occurred in SNP and MNP treated soils, suggesting that long-term additions of organic materials could increase water-holding capacity that, in return, improves water availability to plants and arrests grain yield declines, and sustains productivity.
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