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To reduce the nitrate leaching risk after potato ( Solanum tuberosum L.) harvest and improve nitrogen fertilizer-use efficiency, a potato-cabbage double cropping system (DCS) was established at Hetao, North China, an arid area with irrigated land. A two-year field experiment demonstrated that planting early-maturing potato cultivar under plastic mulch shortened its growth period by 14 d and allowed a second crop of cabbage to scavenge the soil residual NO 3 − S-N to a depth of 160 cm, substantially reducing the risk of nitrate leaching into groundwater. The yearly total N uptake in DCS was about 110 kg ha −1 more than that in the conventional cropping system (CCS), i.e., mono potato planting. This accounted for apparent nitrogen recovery (ANR) improvement of 16.90%–26.57% in the DCS as compared to that in the CCS for both years. As a result, the soil residual NO 3 − -N in the 0–160 cm soil profile in the DCS was lower than that in the CCS. The solar energy-use efficiency and soil-use efficiency were also substantially increased with DCS. |
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