设施蔬菜大棚土壤氮磷钾养分富积降低土壤钙素的有效性

韩巍; 赵金月; 李豆豆; 郭磊磊; 窦莉洋; 刘静; 李嵩; 依艳丽

doi:10.11674/zwyf.17433

设施蔬菜大棚土壤氮磷钾养分富积降低土壤钙素的有效性

Accumulation of NPK nutrients tend to decrease the effectiveness of calcium in greenhouse soil in the long term

摘要

摘要:
目的随着种植年限的增加，设施农业缺钙性生理病害发生率迅速上升。设施土壤中氮磷钾元素的富积与土壤中钙素的形态及有效性有密切关系，进而影响植物对钙素的吸收。因此，本研究调查比较了不同种植年限设施菜地土壤钙素有效性的变化，及与N、P、K含量的关系，为提高土壤钙素有效性和减少缺钙性生理病害提供理论依据。
方法在辽宁省海城市选取了38个设施蔬菜大棚，种植年限在3～30年不等，土壤均为棕壤，按照每三年为一个时间段，将大棚分为9组。采集了棚内0—20 cm的耕层土壤样品，同时采集棚外露地0—20 cm土壤样品作为对照。分析了有机质、氮、磷、钾养分含量，分别测定了土壤水溶性钙、交换性钙、酸溶性钙、非酸溶性钙含量，利用回归方法计算了氮磷钾含量与四种形态钙含量之间的关系。
结果随着种植年限延长，设施土壤有机质、氮、磷、钾、总钙、酸溶性钙和非酸溶性钙含量逐年增加，水溶性钙和交换性钙分别在种植达到9～11年和12～14年时达到最大值104.1和611.9 mg/kg，之后呈下降趋势。总钙增加量的94.3%～96.4%属无效态的非酸溶性钙。土壤中氮、钾含量的提高促进了交换性钙的解吸，铵态氮和速效钾含量与交换性钙呈显著负相关 (r = –0.5451，P <0.01；r = –0.4809，P <0.01，n = 38)。土壤中磷含量的提高促进了难溶性磷酸钙盐的形成，磷酸高钙盐与无效性的非酸溶性钙呈极显著正相关(r = 0.5884，P <0.01，n = 38)。种植30年的设施土壤有效态钙含量与有效氮、磷、钾的比例比露地土壤下降了近70%。
结论随着设施蔬菜种植年限的增加，土壤中的氮、磷、钾养分含量不断增加。氮和钾含量的增加促进了交换性钙的解吸，磷的增加促进了水溶态和交换态钙向无效的非酸溶性钙的转化。因此，土壤中氮磷钾的富积加剧了蔬菜土壤有效性钙的缺乏。

Abstract:
Objectives Physiological diseases induced by calcium deficiency frequently occur under continuous vegetable cultivation. The accumulation of nitrogen, phosphorus and potassium in vegetable soils affects the forms and availability of calcium, which further impacts the uptake of calcium by plants. In this paper, the differences of calcium availability in greenhouse vegetable soil during various planting years were compared, and the relationships with N, P, and K were studied.
Methods Thirty-eight vegetable greenhouses were chosen for the investigation from Haicheng City, Liaoning province. The planting years lasted from 3 to 30 years. The contents of organic matter, available N, P and K in 0–20 cm deep of soils were analyzed. The contents of water soluble, exchangeable, acid-soluble and non-acid soluble calcium were extracted, and their relations with the concentration of N, P, and K were calculated with linear regression analysis.
Results The contents of soil organic matter, N, P, K, total Ca and non-acid-soluble Ca in all the tested greenhouses had kept increasing with the extending of planting years, the water-soluble Ca contents reached maximum of 104.1 mg/kg on the 9th–11th year and the exchangeable Ca contents reached maximum of 611.9 mg/kg on the 12–14 planting years, respectively, and then declined. About 94.3%–96.4% of total Ca was non-acid-soluble Ca. A significantly negative relationship existed between exchangeable Ca and NH₄⁺-N (r = –0.5451, P < 0.01, n = 38), and available K (r = –0.4809, P < 0.01, n = 38), which indicated that accumulation of N and K promoted desorption of exchangeable Ca. P accumulation accelerated the formation of insoluble calcium phosphate, and the concentrations of octocalcium phosphate and decacalcium phosphate were significantly and positively correlated with that of non-acid-soluble Ca (r = 0.5884, P < 0.01, n = 38). After 30 years cultivation, the ratios of available Ca to available N, P and K in greenhouse soil decreased by 70% compared with their open field controls.
Conclusions Long-term vegetable cultivation leads to the poor soil nutrient balance between available Ca and available NPK contents. The increased N and K mainly stimulate the release of exchangeable Ca by NH₄⁺ and K⁺ into soil solution, while increased P transfers these available Ca to low effective non-acid soluble form.

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