Controlled release urea with plastic mulch significantly reduces nutrient losses from sloping lands

In order to understand effects of nitrogen sources and plastic mulching on fluxes and pathways of soil nutrient losses, a randomized block experiment design was employed with two factors and four nitrogen (N) sources and simulated runoff observation method. The results showed that N, P and K losses through underground runoff accounted for 71.30%, 6.36% and 8.85% of the nutrients in the total runoff, indicating that surface runoff was the main path for P and K losses and underground runoff was the main path for N loss. Compared to the no mulching treatment, the treatment of controlled-release urea under plastic mulching effectively reduced N loss by 40.41% from the underground runoff and by 29.30% from the surface runoff. The total N losses in runoff from no mulching treatments were in the sequence of nitrate-N > amide-N>ammonium-N >controlled-release N. Under plastic mulching, total N lost through runoff was observed in the sequence of ammonium-N>amide-N> nitrate-N> controlled-release N. The minimum N loss was in the controlled-release N treatment with plastic mulching, 59.60% less than the ammonium-N treatment. In order to effectively control nutrient losses through water runoff and soil erosion from the purple hilly area in Sichuan, it is best to use controlled-release N with plastic mulching if applicable.

Fig. 1 Fertilization plus plastic mulching is adopted by farmers on sloping lands