酸性土壤施用石灰提高作物产量的整合分析

【目的】施用石灰是改良土壤酸度获得作物增产的传统而有效的方法之一,整合分析石灰增加作物产量的效应和原因,对科学合理施用石灰维持作物高产提供指导。【方法】收集已公开发表有关石灰改良酸性土壤的文献数据,建立土壤p H和作物产量/生物量数据库。分析土壤初始p H(3.1—6.6)、作物类型(粮食作物、经济作物)、石灰施入量(750、750—1 500、1 500—3 000、3 000—6 000、6 000 kg·hm-2)和石灰类型(生石灰、熟石灰、石灰石粉)下,作物的增产率。【结果】与不施石灰相比,酸性土壤上施用石灰可提高作物产量,增产幅度为2%—255%,粮食类作物和经济类作物增产率分别为42%和47%,其中粮食类作物增产率大小排序:玉米(149%)高粱(142%)麦类(55%)豆类(32%)水稻(4%)薯类(2%),经济类作物增产率排序:蔬菜(255%)牧草(89%)油菜(26%)水果(23%)烟草(7%)。施用石灰作物增产率随土壤初始p H的升高呈先升高后降低趋势:当p H为4.3时,增产效果最好,达99%;p H 5.8以上出现减产。在常见土壤酸性范围(p H 4.5—5.5),石灰用量以3 000—6 000 kg·hm-2最佳,增产率达55%—173%。熟石灰的增产效果(100%)要优于生石灰(32%)和石灰石粉(64%)。施用石灰提高土壤p H和交换性钙含量、降低交换性铝含量,是作物增产的主要原因,且当交换性钙为6.2 cmol·kg~(-1)时增产率最大,也证实改良土壤酸度时需要中等石灰用量。【结论】酸性土壤添加石灰对蔬菜和玉米的增产效果最好,并优先选用熟石灰。石灰用量以3 000—6 000 kg·hm-2为宜,在p H大于5.8时不宜施用,即酸性土壤改良目标值为p H 5.8。

Integrated Analysis of Liming for Increasing Crop Yield in Acidic Soils

【Objective】 Application of lime is one of the traditional and effective methods for improving soil acidity to obtain crop yield, so it is very important to integratedly analysis of the effect and cause during liming to increase yield of crops by scientific and rational application of lime to maintain crop yield. Sustain crop production in acidic soils by rational application of lime.【Method】 The published data from 76 studies were collected, a relational database of soil pH-crop yield/biomass was developed. Then the crop growth rate (CGR) was assessed under initial soil pH (3.1-6.6), crop species (cereal crops, cash crops), application rate of lime (＜750, 750-1 500, 1 500-3 000, 3 000-6 000,＞6 000 kg·hm^-2) and lime type (calcium lime, slacked lime, limestone powder). 【Result】Compared to control (without liming), crop yield was promoted by liming in acidic soils, with CGR ranging from 2% to 255%, where CGR was 42% and 47% for cereal crops and cash crops, respectively, and where the order for cereal crops was maize (149%)＞sorghum (142%)＞wheat (55%)＞bean (32%)＞rice (4%)＞tuber (2%), whereas the order for cash crops was vegetable (255%)＞pasture (89%)＞rape (26%)＞fruit (23%)＞tobacco (7%). Under application of lime, with increasing initial soil pH, CGR first increased, reached a maximum where 99% at pH 4.3 was found, and then decreased, even less than zero at pH 5.8. In common acidic soils (pH 4.5-5.5), the optimal application rate of lime ranged from 3 000 to 6 000 kg·hm^-2, where CGR could reach 55%-173%. In addition, slacked lime showed the best effect on increasing crop yield, where CGR was 100%, higher than that of calcium lime (32%) and limestone powder (64%). Application of lime to improve soil pH and exchangeable calcium, decreased exchangeable aluminum content, which was the main cause of increased crop yield under application of lime to acidic soils. However, CGR reached the maximum at ΔpH was 1.5 and exchangeable calcium was 6.2 cmol·kg^-1, suggesting that a moderate amount of lime should be applied during ameliorating soil acidity. 【Conclusion】 The highest priority should be given to vegetable and maize when application of lime to acidic soils, and slacked lime would be employed as the first choice. The application rate of lime was recommended to be 3 000-6 000 kg·hm^-2, and no lime was applied at pH more than 5.8. That is, the pH target 5.8 should be set and correspondingly lime requirement be determined for amelioration of soil acidity.