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  • Author or Editor: Shichao Wang x
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Shichao Wang, Xinlu Bai, Jianbin Zhou and Zhujun Chen

Overapplication of nutrients and water is common in intensive greenhouse systems. A 2-year experiment (2011–13) was conducted to study the effect of different nutrient and water treatments on the growth and yield of tomato (Lycopersicum esculentum Mill.) and on soil nutrient accumulations in solar greenhouses in South Loess Plateau, China. The treatments included 1) current fertilizer and water practices (FW), 2) formula fertilizer and water 1 (FW1), 3) formula fertilizer and water 2 (FW2), and 4) farmer’s practice (FP). Compared with FW, FW1 and FW2 had yields not significantly different from grower control treatments; however, they saved 35% to 46% of the nitrogen (N) fertilizer, 40% to 54% of the phosphorus (P2O5) fertilizer, 19% to 35% of the potassium (K2O) fertilizer, and 15% to 21% of irrigation water. The economic profits of FW1 and FW2 were greater than those of the FW and FP treatments. The two formula treatments also reduced soil electrical conductivity (EC) and the accumulation of nitrate, available P, and available K in soil. However, the soil nutrients are still above optimal levels. Obvious N surplus in the greenhouse was observed in different treatments, mainly because of high N input from manures. This study revealed there is great potential to reduce nutrient and water use while maintaining the same yield in a greenhouse system.

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Shichao Wang, Zhujun Chen, Jun Man and Jianbin Zhou

In China, greenhouse soils often receive large rates of different manures and have a high content of soil organic matter (SOM). Understanding changes in nitrogen (N) mineralization in soils of newly built greenhouses after their construction is important for managing N. Soil samples were obtained from solar greenhouses of different ages (0, 1, 2, and 3 years) located in the south edge of the Loess Plateau, China, at 0- to 20- and 20- to 40-cm depth. N mineralization in the soils was measured with the Stanford and Smith long-term aerobic incubation method over 30 weeks. SOM, total N, and the mineralized N in the 0- to 20-cm and 20- to 40-cm soil layers were significantly increased in the older greenhouses. The cumulative mineralized N in the 0- to 20-cm soil layer in different cultivation years was increased in each year since the greenhouses were established. For the greenhouses with the same age, the cumulative mineralized N in the 0- to 20-cm soil layer was greater than that in the 20- to 40-cm layer. The potentially mineralizable N (N0) both in the 0- to 20-cm and the 20- to 40-cm soil layers increased with the greenhouses’ age. Regression analysis indicated that when SOM increased 1 g·kg−1, N0 in the 0- to 20-cm and 20- to 40-cm depth increased 22.6 and 8.4 mg·kg−1, respectively. Therefore, as the N supply in soil increases with the age of the solar greenhouse, we suggest that the application rates of manure and synthetic fertilizer be reduced.