海藻渣与镁配施对红壤理化性质和烟草生长的影响

针对部分红壤地区土壤酸性强、有效养分含量低及透气性差等特性,研究了硫酸镁和海藻渣配施对红壤理化性质及烟草生长的影响,为烟区红壤改良提供理论基础。采用盆栽试验,设置6个处理,CK：对照,不加镁和海藻渣;MS：单独施用硫酸镁,每千克土施用0.375 g;SF：单独施用海藻渣,每千克土施用50 g;C₁：每千克土施用MgSO₄ 0.375 g+海藻渣50 g;C₂：每千克土施用MgSO₄ 0.563 g+海藻渣75 g;C₃：每千克土施用MgSO₄ 0.75 g+海藻渣100 g。烟草收获时,测定并分析不同处理对土壤pH、有机碳、矿质养分含量、土壤容重、总孔隙度,以及烟草农艺性状、烟叶矿质养分含量等的影响。结果表明：单独施用硫酸镁或海藻渣以及硫酸镁与海藻渣配施后,烟草株高、茎粗和叶片数等农艺性状明显改善,生物量比对照显著提高;硫酸镁单施处理中烟叶的P和Mg含量比对照显著提高,海藻渣单施及硫酸镁与海藻渣配施的烟叶P、K和Mg含量比对照显著提高;C₃处理土壤pH比对照提高0.38个单位,碱解氮、有效磷、速效钾、交换性钙和交换性镁含量分别比对照提高了42.85%、60.01%、33.73%、253.02%和689.07%;C₁、C₂和C₃处理土壤有机碳含量分别比对照提高了212.9%、385.7%和540.7%;海藻渣单施及与镁配施对土壤有效磷、速效钾、交换性钙和交换性镁含量显著提高;海藻渣单施或与镁配施能显著降低土壤容重并提高土壤总孔隙度;C₃处理土壤容重比对照显著降低9.78%,总孔隙度比对照显著提高8.87%。因此,海藻渣和硫酸镁配施能促进红壤中烟草的生长,并有效改善红壤的理化性状。

Effects of Combined Application of Seaweed Residue and Magnesium on Physicochemical Properties of Red Soil and Tobacco Growth

To improve the soil fertility and tobacco growth in red soil areas for its strong soil acidity, low available nutrient content and poor air permeability, the soil physicochemical properties and tobacco growth with the application of magnesium sulfate and seaweed residue were investigated. A pot experiment with 6 treatments was conducted, i.e., CK: Control, without magnesium and seaweed residue, MS: Single application of 0.375 g magnesium sulfate per 1 kg soil, SF: Single application of seaweed residue 50 g per 1 kg soil, C₁: Application of 0.375 g magnesium sulfate + 50 g seaweed residue per 1 kg soil, C₂: Application of 0.563 g magnesium sulfate +75 g seaweed residue per 1 kg soil, C₃: Application of 0.75 g magnesium sulfate +100 g seaweed residue per 1 kg soil. The effects of seaweed residue and magnesium on soil pH, organic carbon, mineral nutrient content, soil bulk density, and porosity, agronomic characteristics of tobacco and mineral nutrient contents of tobacco leaves were analyzed. The results showed that with the application of magnesium sulfate, seaweed residue alone or magnesium sulfate with seaweed residue, the agronomic traits, such as plant height, stem diameter, leaves of tobacco and biomass were significantly improved. Meanwhile, the contents of P and Mg in the tobacco leaves were significantly increased under the application of magnesium sulfate only. In addition, the contents of P, K and Mg in the tobacco leaves were also significantly higher in the application of seaweed residue alone or combined with magnesium sulfate. Compared with CK, soil pH of C₃ treatment was significantly increased by 0.38 units, and the contents of alkaline - N, available - P, available- K, exchangeable - Ca and exchangeable - Mg were increased by 42.85%, 60.01%, 33.73%, 253.02% and 689.07% respectively. Soil organic carbon content of C₁, C₂ and C₃ treatments increased by 212.9%, 385.7% and 540.7% than that of CK, respectively. The soil pH and soil organic carbon content were increased significantly with magnesium sulfate and seaweed residue application. The contents of available phosphorus, available potassium, exchangeable calcium and magnesium in soil were significantly increased by applying seaweed residue alone or in combination with magnesium. The application of seaweed residue alone or in combination with magnesium could significantly reduce soil bulk density and increase total soil porosity. Compared with CK, C₃ treatment significantly reduced soil bulk density by 9.78%, and increased total porosity by 8.87%. It suggests that the growth of tobacco and physicochemical properties of red soil could be significantly improved by application with seaweed residue.