不同种植密度的夏季填闲作物对设施土壤磷素形态及其迁移性的影响

Effects of Summer Catch Crops with Different Planting Densities on Greenhouse Soil Phosphorus Forms and Mobility

集约化设施土壤磷素积累日益严重,导致土壤磷素环境风险增大。为减轻设施土壤磷素积累,在设施菜田休闲期选用短时期内生物量大、深根系的鲜食糯玉米和饲用甜高粱为供试材料,分别设计了3个不同种植密度,即糯玉米6.75万(NY1),10.50万(NY2),13.50万(NY3)株/hm^2,饲用甜高粱10.50万(TG1),15.00万(TG2),21.00万(TG3)株/hm^2,研究填闲作物磷素吸收量及其对设施土壤磷素含量和磷酸酶活性的影响。结果表明,随种植密度提高,2种填闲作物总生物量和总吸磷量均先增后减,饲用甜高粱处理中TG2处理吸磷量最多,为150.03 kg/hm^2,糯玉米处理中NY2,吸磷量最高,为128.80 kg/hm^2。填闲糯玉米各处理和甜高粱TG1、TG2处理均可显著降低土壤表层总磷含量,分别降低15.2%~19.7%和10.7%~10.9%,2种填闲作物种植处理土壤表层水溶性磷含量分别显著降低28.4%~41.0%和16.2%~26.1%,且NY2、NY3、TG1、TG2处理对阻控下层土壤水溶性磷移动效果较好。另外,填闲糯玉米处理在西兰花种植初期土壤碱性磷酸酶没有明显增加,可以控制土壤有机磷矿化,TG2处理可以降低后茬初期土壤水溶性磷含量。因此,在本试验条件下,设施菜田填闲糯玉米和饲用甜高粱的适宜密度分别为10.50,15.00万株/hm^2,且NY2处理对减少设施土壤磷素积累,阻控磷素向下移动效果较为明显,TG2处理对吸收设施土壤磷素较为明显。

Soil phosphorus accumulation in intensive greenhouse is becoming more and more serious, leading to an increase in soil phosphorus environmental risks. In order to reduce the accumulation of phosphorus in the soil of the greenhouse, this study designed three different planting densities for the short-term high biomass, deep roots of fresh waxy corn and feeding sweet sorghum in the greenhouse vegetable field leisure period. That was, waxy corn 67 500(NY1), 105 000(NY2), 135 000(NY3) plants/ha, feed sweet sorghum 105 000(TG1), 150 000(TG2), 210 000(TG3) plants/ha.The effects of catch crops on their phosphorus absorption, phosphorus content in greenhouse soil, and phosphatase activity were studied.The results showed that the total biomass and total phosphorus uptake of the two kinds of catch crops increased first and then decreased with the increase of planting density.In feeding sweet sorghum treatments,TG2 treatment had the highest phosphorus absorption, which was 150.03 kg/ha, and in waxy corn treatments, NY2 treatment had the highest phosphorus absorption, which was 128.80 kg/ha. Each treatment of waxy corn and TG1,TG2 treatments significantly reduced the total phosphorus content in the soil surface, which decreased by 15.2%-19.7% and 10.7%-10.9%. The treatment of different catch crops significantly reduced the water-soluble phosphorus content in the soil surface by 28.4%-41.0% and 16.2%-26.1%. NY2, NY3, TG1 and TG2 treatments had a better effect on the control of water-soluble phosphorus in the lower layer soil. In addition, the alkaline phosphatase of the treatment of waxy corn did not increase significantly at the early stage of planting broccoli, which could control the organic phosphate mineralization in the soil. TG2 treatment could reduce the water-soluble phosphorus content in the early post-stubble soil.Therefore, under the conditions of this experiment, the suitable density of waxy corn and feeding sweet sorghum in the greenhouse vegetable field were 105 000,150 000 plants/ha, NY2 treatment had a significant effect on reducing the accumulation of phosphorus in the soil and controlling the downward movement of phosphorus,TG2 was more obvious for absorbing soil phosphorus in the greenhouse.