长期耕作对新疆绿洲农田土壤颗粒中有机碳和全氮含量的影响

doi:10.3864/j.issn.0578-1752.2020.24.007

摘要/Abstract

摘要：

【目的】土壤颗粒中有机碳和全氮是土壤有机碳和全氮的重要组成部分,研究长期耕作对农田土壤颗粒组分中有机碳和全氮组分含量和比例变化的影响,有助于揭示不同耕作年限下土壤有机碳和全氮的固存与周转规律,可为区域农田土壤培肥和固碳减排提供科学依据。【方法】以天山南北3个典型绿洲（兰州湾镇、31团、普惠农场）长期耕作农田土壤为研究对象,采用土壤颗粒分级法,研究不同耕作年限（0、5、10、15、20年）下3个典型绿洲农田土壤有机碳和全氮的变化规律,分析长期耕作对不同颗粒组分中有机碳和全氮含量的影响。【结果】（1）长期耕作增加了土壤有机碳和全氮的积累,并随耕作时间的延长而趋于平稳。与未耕作土壤相比,耕作0—5 a间,土壤有机碳、全氮含量增加迅速,兰州湾镇、普惠农场和31团土壤有机碳含量分别提高了76.4%、286.2%和145.6%,土壤全氮含量提高了14.7%、58.9%和75.0%,耕作5 a后,增速趋于平缓。（2）耕作提高了不同颗粒组分中有机碳和全氮含量,砂粒中有机碳含量表现为先增加后下降的趋势,与未耕作土壤相比,兰州湾、31团和普惠农场在耕作10—15 a间达到峰值,随后下降;耕作20 a后土壤砂粒中有机碳含量分别增加了0.63、0.89和1.56 g·kg^-1。而粉粒和黏粒中有机碳含量随耕作时间延长表现为持续增加,耕作20 a后,兰州湾、31团和普惠农场粉粒和黏粒中有机碳含量分别增加了0.42-2.39、2.64-3.39、1.36-2.72 g·kg^-1。耕作年限对不同颗粒组分中全氮含量的影响比较复杂,砂粒中全氮含量表现为随耕作时间呈现逐渐增加的趋势,耕作20 a后,兰州湾、31团和普惠农场砂粒中全氮含量分别增加了0.24、0.40和0.29 g·kg^-1;粉粒中全氮含量随耕作时间呈现先下降（0—10 a）,而后（10—20 a）上升的趋势,而黏粒中全氮含量则表现为相反的趋势,耕作0—10 a间快速增加,耕作10 a后开始下降。（3）不同颗粒组分中,粉粒中有机碳和全氮含量占比最大,分别在43.3%—56.1%和30.2%—72.2%之间。耕作改变了不同颗粒组分中有机碳和全氮含量在土壤有机碳和全氮中的分配比例,耕作0—10 a 间,砂粒中有机碳分配比例逐渐增加,10—20 a间呈降低趋势,砂粒中全氮比例分配则随耕作时间表现出递增趋势,耕作20 a间,兰州湾、31团和普惠农场,砂粒中全氮分配比例分别增加了14.8%、19.8%和29.0%。（4）耕作提高了土壤碳氮比,耕作0—5 a间,土壤中碳氮比迅速提高40.3%—142.9%,5 a后,碳氮比变化不明显,同时,改变了不同颗粒组分中碳氮比,耕作0—10 a,砂粒中的碳氮比最高,10 a后,粉粒中碳氮比最高。【结论】耕作增加了新疆绿洲农田土壤有机碳和全氮含量,改变了不同颗粒组分中土壤有机碳和全氮含量和占比,有助于土壤有机碳和全氮的累积,其中粉粒中的有机碳和全氮是该地区土壤固持有机碳和全氮的主体。

关键词: 耕作, 颗粒组分, 碳氮比, 有机碳, 全氮, 绿洲农田, 新疆

Abstract:

【Objective】Particulate organic carbon and total nitrogen are the important components of soil organic carbon (SOC) and total nitrogen (TN), which has an effect on SOC and TN turnover and sequestration. Therefore, studies exploring the changes in soil particulate organic carbon and total nitrogen under different tillage years could aid the understanding of the mechanism of regional soil carbon and nitrogen fixation, so as to provide a scientific basis for improving land productivity. 【Method】In this study, soil samples from the farmlands with different tillage years (0, 5, 10, 15, and 20 years) in the three typical oases (Lanzhouwan, 31 corps, and Puhui farms) of Tianshan were collected, and the SOC and TN contents of different particle components were determined. And then, the effects of long-term tillage on SOC and TN contents of different particle components were analyzed. 【Result】Results indicated that long-term tillage practices increased SOC and TN accumulation. SOC and TN contents increased rapidly during the first five years of tillage and then tended to be stable after five years of tillage. SOC contents increased to 76.4% (Lanzhouwan), 286.2% (31 corps), and 145.6% (Puhui farms) of the SOC contents in uncultivated land. Similarly, TN contents increased to 14.7%, 58.9%, and 75.0%, respectively. The effects of long-term tillage practices on OC contents in different particles components were different. The organic carbon (OC) contents in sand showed a downward trend after reaching a maximum value (10-15 years tillage), and then showed a increasing trend, but it remained higher than that of an uncultivated land. After 20 years of tillage, OC contents in sand were increased by 0.63 g·kg^-1 (Lanzhouwan), 0.89 g·kg^-1 (31 corps), and 1.56 g·kg^-1 (Puhui farms). While, the contents of OC in silt and clay showed a continuous increasing trend with tillage time, After 20 years of tillage, OC contents in silt and clay were increased by 0.42-2.39 g·kg^-1 (Lanzhouwan), 2.64-3.39 g·kg^-1 (31 corps), and 1.36-2.72 g·kg^-1 (Puhui farms). However, the effect of long-term tillage practices on TN in different particles components was complex. The OC contents in sand showed a continuous increasing trend, After 20 years of tillage, TN contents in sand were increased by 0.24 g·kg^-1 (Lanzhouwan), 0.40 g·kg^-1 (31 corps), 0.29 g·kg^-1 (Puhui farms).. The content of TN in silt decreased (0-10 years of tillage) initially and then increased (10-20 years). TN in clay increased by 67.6% in Lanzhouwan, 306.3% in 31 corps, and 91.3% in Puhui farms during 0-10 years of tillage and decreased after 10 years of tillage. With regard to particle components, OC and TN in silt had the largest proportions, accounted for 43.3%-56.1% and 30.2%-72.2% of SOC and TN, respectively. Tillage affected the distribution proportions of OC and TN in different components. The distribution proportion of OC in sand increased during the first 10 years and decreased in the subsequent 10 years. The distribution proportion of TN in sand was increased by 14.8% in Lanzhouwan, 19.8% in 31 corps, and 29.0% in Puhui farms after 20 years of tillage. Soil C/N was increased by 40.3%-142.9% during 0-5 years of tillage, and no significant change was observed after 5 years of tillage. Tillage changed C/N ratio in different particles components, and the largest C/N ratio was obtained in sand during 0-10 years of tillage. During the subsequent 10 years, the largest C/N ratio was obtained in silt. 【Conclusion】The SOC and TN contents and their stocks increased over tillage years in the oasis farmland of Xinjiang. The contents and its distribution proportions of OC and TN in different particles components were also changed. We found that the contents of OC and TN in silt fraction were the largest components of the fixed SOC and TN in the study area.

Key words: tillage, particulate component, carbon-nitrogen ratio, Oasis farmland

唐光木,张云舒,徐万里,马海刚,胡克林. 长期耕作对新疆绿洲农田土壤颗粒中有机碳和全氮含量的影响[J]. 中国农业科学, 2020, 53(24): 5039-5049.

TANG GuangMu,ZHANG YunShu,XU WanLi,MA HaiGang,HU KeLin. Effects of Long-Term Cultivation on Contents of Organic Carbon and Total Nitrogen in Soil Particulate Fraction in Oasis Farmland of Xinjiang[J]. Scientia Agricultura Sinica, 2020, 53(24): 5039-5049.

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采样点 Sampling site	pH	容重 Bulk density (g·cm^-3)	碱解氮 Available N (mg·kg^-1)	速效磷 Available P (mg·kg^-1)	速效钾 Available K (mg·kg^-1)	电导率 EC (mS·cm^-1)	阳离子交换量 CEC (cmol·kg^-1)
兰州湾 Lanzhouwan	8.18±0.19	1.41±0.18	53.33±45.97	14.07±21.43	380.00±144.00	1.66±0.69	11.31±9.11
31团 31 corps	8.03±0.09	1.41±0.19	50.25±6.32	28.72±8.21	135.00±9.40	0.58±0.09	10.56±1.26
普惠农场 Puhui farm	7.92±0.13	1.47±0.13	47.35±10.32	60.09±28.17	128.40±23.84	1.21±0.51	9.37±1.86

采样区 Sampling site	耕作年限 Tillage year （a）	砂粒 Sand（>50 μm）		粉粒 Silt（2-50 μm）		黏粒 Clay（<2 μm）
采样区 Sampling site	耕作年限 Tillage year （a）	有机碳 Organic carbon (g·kg^-1)	全氮 Total nitrogen (g·kg^-1)	有机碳 Organic carbon (g·kg^-1)	全氮 Total nitrogen (g·kg^-1)	有机碳 Organic carbon (g·kg^-1)	全氮 Total nitrogen (g·kg^-1)
兰州湾 Lanzhouwan	0	0.40±0.12c	0.07±0.00d	1.57±0.50c	0.56±0.05ab	1.65±0.20d	0.37±0.01d
	5	1.10±0.57b	0.09±0.00d	2.95±0.59b	0.52±0.03b	2.34±0.13bc	0.56±0.07ab
	10	1.25±0.74a	0.16±0.02c	3.03±0.35b	0.49±0.04b	2.48±0.47ab	0.62±0.05bc
	15	1.02±0.38b	0.24±0.01b	3.11±0.86b	0.61±0.07ab	2.88±0.22a	0.48±0.05a
	20	1.03±0.58b	0.31±0.07a	3.96±0.49a	0.69±0.10a	2.07±0.21c	0.40±0.04cd
31团 31 corps	0	0.32±0.18d	0.02±0.00d	1.02±0.70d	0.53±0.02a	0.57±0.20c	0.16±0.01c
	5	1.34±0.34b	0.14±0.01c	3.39±0.49c	0.42±0.07a	2.61±0.69b	0.59±0.11ab
	10	1.52±0.78a	0.21±0.03b	3.72±0.91b	0.38±0.01a	2.54±0.37b	0.65±0.09a
	15	1.31±0.50bc	0.25±0.01ab	4.15±0.58a	0.47±0.06a	2.77±0.18b	0.54±0.03b
	20	1.21±0.96c	0.31±0.05a	4.41±0.47a	0.54±0.03a	3.21±0.32a	0.49±0.07b
普惠农场 Puhui farm	0	0.42±0.44c	0.04±0.00d	1.04±0.17d	0.32±0.00b	0.77±0.29c	0.23±0.01d
	5	1.51±0.96b	0.19±0.01c	2.39±0.51c	0.41±0.05b	1.59±0.29b	0.39±0.04b
	10	1.72±0.11ab	0.36±0.03b	2.41±0.50c	0.43±0.03b	1.75±0.24ab	0.44±0.03a
	15	2.05±0.79a	0.42±0.02ab	3.41±0.70b	0.58±0.09a	2.00±0.23ab	0.36±0.01c
	20	1.98±0.17a	0.51±0.06a	3.76±0.76a	0.64±0.11a	2.13±0.47a	0.25±0.00d

采样区 Sampling site	耕作年限 Tillage year （a）	土壤碳氮比 C/N	颗粒组分碳氮比C/N in particle fractions
采样区 Sampling site	耕作年限 Tillage year （a）	土壤碳氮比 C/N	砂粒Sand (>50 μm)	粉粒Silt (2-50 μm)	黏粒Clay (<2 μm)
兰州湾 Lanzhouwan	0	3.55±0.97b	6.14±0.12bc	2.82±0.55b	4.41±0.21bc
	5	5.46±0.70a	12.22±0.57a	5.72±0.62a	4.16±0.20c
	10	5.24±0.78a	7.81±0.76b	6.16±0.39a	4.00±0.52c
	15	5.23±0.86a	4.32±0.39cd	5.08±0.93a	6.00±0.27a
	20	4.77±0.95ab	3.28±0.65d	5.71±0.59a	5.16±0.25ab
31团 31 corps	0	2.61±0.36b	18.16±0.18a	1.94±0.72c	3.46±0.21d
	5	6.34±0.62a	9.43±0.35b	8.16±0.56b	4.46±0.80c
	10	6.14±0.73a	7.12±0.81c	9.71±0.92ab	3.88±0.46cd
	15	6.10±0.40a	5.23±0.51cd	8.77±0.64ab	5.17±0.21b
	20	6.31±0.38a	3.89±1.01d	8.12±0.50b	6.53±0.35a
普惠农场 Puhui farm	0	3.72±0.48c	10.14±0.44a	3.28±0.17b	3.38±0.30d
	5	5.22±0.32ab	8.07±0.97b	5.85±0.56a	4.07±0.33c
	10	4.78±0.46b	4.78±0.14c	5.60±0.53a	3.96±0.27c
	15	5.43±0.58ab	4.88±0.81c	5.86±0.79a	5.59±0.24b
	20	5.54±0.73a	3.88±0.23b	5.84±0.87a	8.41±0.47a