Objectives The effect of different fertilization patterns on the yield increase of spring maize and winter wheat and the stability and sustainability of the increment were studied under different precipitation years, which will provide scientific basis for efficient management of nutrient resources in the crop production of rainfed area.
Methods The study was based on the long-term fertilization experiment established in Pingliang City, Gansu Province in 1979. The experiment had lasted for 38 years, of which, the number of dry, normal and wet years was 9, 7 and 10 for winter wheat and 7, 2 and 3 for spring maize. There were six treatments, including: no fertilizer (CK), single chemical nitrogen fertilizer (N), nitrogen-phosphorus fertilizer (NP), straw + nitrogen-phosphorus fertilizer (SNP), single organic fertilizer (M) and organic fertilizer + nitrogen-phosphorus fertilizer (MNP). We investigated the yields of winter wheat and spring maize, calculated yield stability and yield sustainable index (SYI), fertilizer contribution rate to yield (FCR) and rainfall use efficiency (RUE), and the relationships among the yield, fertilization patterns and precipitation.
Results Compared with N treatment, the yields of winter wheat under NP, SNP, M, and MNP treatments significantly increased in all the dry, normal and wet years by 89.8%–151%, 108%–174%, and 52.1%–101.9%, the yields of spring maize were increased by 56.3%–99.9%, 81.3%–104%, and 105%–127%, respectively. The precipitation did not affect the stability and sustainability of winter wheat yield significantly, but affected those of spring maize. Compared to N treatment, the FCR and RUE of winter wheat under NP, SNP, M, and MNP treatments in the dry and wet years were significantly increased by 166%–198%, 520%–654% and 100%–164%, 53.4%–105%, respectively, and those of spring maize were increased by 161%–218%, 262%–289% and 56.0%–99.2%, 104%–125%. Compared to the dry year and under the same fertilizer pattern, the FCR of winter wheat under NP, SNP, M and MNP treatments were decreased by 9.9%–23.3% in normal years and by 10.6%–23.3% in wet years, while the FCR of maize in wet years were 6.0%–25.0% higher than those in dry years and 20.4%–27.7% higher than in normal years. Compared to dry years, the RUE of winter wheat under NP, SNP, M and MNP treatments were decreased by 2.2%–26.6% in normal years and 22.3%–37.7% in wet years, and those of maize were decreased by 41.9%–49.5% in normal years and 10.9%–24.4% in wet years. The yields of winter wheat and spring maize were closely related to fertilization patterns and precipitation in growth periods in different precipitation years.
Conclusions In Loess Plateau of east Gansu Province, the yield, the stability and sustainability of yield, the contribution rate of fertilizer to yield and rainfall use efficiency of crops are significantly improved by both the combination use of NP fertilizers with straw returns or manures, regardless of precipitation. Thus, they are two effective fertilization strategies to guarantee the sustainable and efficient crop production in the dry farmland in this area. Further optimization in fertilization details is required in term of precipitation years.
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