Objectives Combining application of chemical and organic fertilizers has been found an effective way to reduce fertilizer losses and improve fertilizer utilization in crop production. The effects of reducing chemical fertilizer rate and compensation nutrient amount with organic fertilizers on soil nutrient availability and maize yield were studied in this paper under straw returning to field in strips.
Methods Field experiments were carried out consecutively in 2018 and 2019 in a chernozem soil where maize is mono-cropped all the time. The treatment plots were separated by returning maize straw to field in strips, and there are a total of four fertilization treatments in the experiment: NPK compound fertilizer in conventional application rate (T1) and in 20% less application rate (T2), and compensate the reduced 20% N rate with chicken manure (T3) or cow manure (T4). The soil organic carbon and available nutrient contents were measured at the jointing and harvest periods of the maize each year, as well as the corn yield.
Results Compared with T1 treatment, reducing 20% of fertilizer input (T2 treatment) did not reduce the maize yields for two consecutive years, but decreased the soil available nutrient contents, especially in the second experimental year; Compensating the reduced nutrient input with chicken or cattle manure (T3 and T4 treatments) significantly increased the contents of soil organic carbon and available nutrients, and the maize yields. The T3 treatment had the most profound influence on the soil nutrients for the two consecutive years. In the first year, the contents of organic C, alkaline N, available P, and available K in T3 treatment were increased by 15.2%, 12.2%, 16.7%, and 7.75%, respectively and 13%, 18.5%, 34.2%, and 18.5% respectively for the second year. The maize yield in T3 treatment increased by 3.75% and 15.4% in the first and second year respectively. T4 treatment had the most striking effect, increasing the maize yield by 5.6% and 20.8% in the first and second year respectively, compared to T1. Correlation analysis revealed that the soil organic C and available N, P and K were all significantly correlated with maize yield.
Conclusions Under condition of returning maize straws to the field in strips, replacing 20% of conventional NPK inputs with manures shows sounded effect in increasing soil fertility and obtaining higher yield. Chicken manure is more effective than cattle manure in chernozem soil.
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