Nutrient Losses from Sloping Lands as Affected by Surface Mulching and Cultivation in Sichuan

IPNI-2009-CHN-SC17

04 Jan 2012

2011 Annual Interpretive Summary

Nutrient Losses from Sloping Lands as Affected by Nitrogen Sources and Surface Mulch in Sichuan, 2011

The objective of this project was to further evaluate the effects of different N sources and surface mulching methods on corn yield and nutrient losses from Sichuan’s sloping farmlands during the summer rainy season. There were four N sources including ammonium N (ammonium bicarbonate, ABC), nitrate N (calcium nitrate), amide N (urea), and controlled-release (CRU) urea and three types of surface mulching (no mulch, wheat straw, and plastic film) employed in the field experiment. The fertilizer rates were 300-150-150 kg N-P2O5-K2O/ha based on the previous experiments.

Results showed that mulching the soil with wheat straw or plastic film significantly increased corn yield by 6.4% or 7.2 % compared to the no mulch treatment. This further confirmed that any methods that could conserve more soil moisture and prevent soil erosion and nutrient losses could produce more corn yield on the non-irrigated sloping lands.

Among the four N sources without surface mulch, CRU produced the highest corn yield, followed by urea, calcium nitrate, and ABC. When combined with surface mulch, all N sources significantly enhanced corn yields. It is of interest that CRU and ABC were equally superior to urea and calcium nitrate on corn yields. Ammonium bicarbonate use under wheat straw mulch slightly reduced corn yield compared to ABC under plastic mulch. Ammonium bicarbonate, an inferior N source, once dominated China’s N fertilizer market, but today is of least importance, performed the best under surface mulch, indicating that different agronomic practices can affect the performance of a fertilizer considerably. By further analyzing amounts of soil erosion and nutrient losses caused by different treatments, we determined that mulching treatments significantly reduced nutrient losses through reduced soil erosion (44 to 58%) and reduced leaching or surface runoff (4.1 to 20.3 mm), enhanced N uptake by corn and finally corn yields, the same trend reported in the previous years. Sichuan-BFDP-09