土壤团聚体组分中碳钾分配对芋头-水稻轮作年限的响应
Responses of carbon and potassium contents in soil aggregates to the duration of taro-rice rotation
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摘要:
赣东北地区的芋头-水稻轮作发展迅速,但较高的有机肥投入和持续的秸秆还田对土壤团聚体碳钾的影响程度还不明确,因此,亟需开展芋头-水稻轮作不同年限下土壤团聚体碳钾分配机制方面研究,为芋头-水稻轮作模式科学施肥提供理论依据。试验于2020年在江西省上饶市铅山县湖坊镇进行,分别选取芋头-水稻轮作1年、3年、5年、10年的田块,以只种植一季水稻的田块(CK)为对照,测定其土壤肥力、土壤中各团聚体组分及各组分团聚体中有机碳、全钾和速效钾含量,并进一步分析团聚体组分中有机碳与速效钾的相关关系。结果表明,芋头-水稻轮作可以改善土壤酸化程度,提高土壤肥力,且土壤肥力随轮作年限的延长呈上升趋势。不同轮作年限能改变土壤中各团聚体组分的比例,随着轮作年限的延长,>2 mm大团聚体比例不断增加,在轮作5年时显著高于CK处理。>2 mm,0.25~2 mm,0.053~0.25 mm团聚体中有机碳浓度随轮作年限的延长呈上升趋势,在轮作10年时达到最大,较CK处理分别显著提高了18.6%、40.9%、29.9%。与CK处理相比,>2 mm团聚体中全钾含量在轮作5年时显著增加,较CK处理显著增加了13.6%,随着轮作年限的延长持续增加,但增加幅度较小;速效钾含量在轮作3年时显著增加,至轮作10年时,较CK增加了2.24倍。相关分析表明,>2 mm团聚体中有机碳与速效钾含量呈显著正相关关系,结合线性方程的斜率发现,当>2 mm团聚体中的有机碳浓度增加0.10 g · kg-1,速效钾含量提高3.30 mg · kg-1。因此,芋头-水稻轮作可以提升我国赣东北地区土壤肥力,提高土壤中大团聚体的比例及有机碳的含量,进而促进土壤钾素的积累,满足作物对钾素的需求。
Abstract:The taro (Colocasiaes culenta)-rice (Oryza sativa) rotation has been rapidly developed in the northeastern area of Jiangxi Province in recent years.However, the influence of high organic fertilizer input and continuous straw returning on soil aggregate carbon and potassium (K) is not clear.Thus, it is essential to study the distribution of carbon and K contents in soil aggregates under taro-rice rotation with different cultivation years, which can provide theoretical basis for optimal fertilization in taro-rice rotation system.In 2020, we selected taro-rice rotation for one year, three years, five years and ten years as the treatments, and one season of rice cultivation as a control (CK) in Hufang Town of Yanshan County in Shangrao City of Jiangxi Province.We determined the soil fertility, aggregate components and their organic carbon and potassium contents; further analyzed the correlation between the contents of organic carbon and available K in each aggregate component.The results showed that taro-rice rotation alleviated soil acidification, and greatly improved soil fertility with increasing rotation years.Rotation years changed the proportion of soil aggregates, and the proportion of large aggregates (>2 mm) increased with increasing rotation years.The proportion of large aggregates (>2 mm) in 5-year rotation treatment was significantly higher than that of CK treatment.The organic carbon contents in the >2 mm, 0.25~2 mm, 0.053~0.25 mm aggregates increased with increasing rotation years, and reached the maximum value at 10-year rotation, which was significantly increased by 18.6%, 40.9% and 29.9% relative than that of CK treatment, respectively.The total K contents in the >2 mm aggregate increased significantly by 13.6% in 5-year rotation than that of CK.With increasing rotation years, total K contents continued to increase, but the increased magnitude became smaller.Compared with CK, the available K contents in the >2 mm aggregate in 3-year rotation treatment significantly increased by 2.24 fold.There was a significantly positive correlation between organic carbon and available K content in > 2 mm aggregates (R2=0.93, P < 0.05).The slope of linear equation suggested that the available potassium content increased by 3.30 mg · kg-1 when the organic carbon increased by 0.10 g · kg-1 in > 2mm aggregates.In conclusion, taro-rice rotation improves soil fertility and increases the proportion of organic carbon in large aggregates, thus facilitating soil K accumulation to meet crop growth requirement.