免耕结合覆盖措施对渭北旱塬黑垆土结构与团聚体有机碳含量的影响

doi:10.3864/j.issn.0578-1752.2023.12.008

摘要/Abstract

摘要：

【目的】阐明长期免耕及覆盖措施对渭北旱塬农田土壤团聚体结构和有机碳含量的影响，探索改善区域土壤的适宜耕作措施。【方法】在连续16年的黑垆土田间定位试验中选择传统耕作（CT）、免耕无覆盖（NT）、免耕+秸秆覆盖（NS）、免耕+地膜覆盖（NP）、免耕+秸秆覆盖+地膜覆盖（NSP）等共5种田间管理措施，于2019年10月春玉米收获期采集0—40 cm土层土样，测定容重、团聚体粒级分布及有机碳含量。【结果】（1）免耕及覆盖措施（NT、NP、NS和NSP）影响了黑垆土容重和团聚体粒级分布。免耕及覆盖措施均提高了耕层（0—20 cm）土壤容重，其中0—10 cm土层容重提高7.1%—17.8%，犁底层容重和孔隙度变化与耕层相反。耕层大团聚体比例显著提高、微团聚体比例显著降低，促进耕层微团聚体向大团聚体的转化。各粒级团聚体重量百分比在耕层（0—20 cm）分布为：较大团聚体（0.25—2 mm）>大团聚体（>2 mm）>微团聚体（0.053—0.25 mm）>粉黏粒组分（<0.053 mm），在犁底层（20—40 cm）为较大团聚体和粉黏粒组分显著高于大团聚体和微团聚体。（2）免耕及覆盖措施下有机碳含量随团聚体粒级增大而增加。在0—40 cm土层，NT处理各粒级团聚体有机碳含量均显著低于CT处理，而NS、NSP处理均显著高于CT处理。（3）耕层总有机碳累积以>0.25 mm团聚体有机碳为主，犁底层以粉黏粒组分和较大团聚体有机碳为主。【结论】长期免耕及覆盖措施促进耕层微团聚体向大团聚体转化。与传统耕作相比，免耕和地膜覆盖均降低了耕层各粒级团聚体有机碳含量。而免耕覆盖（NS、NP和NSP）比免耕无覆盖（NT）均增加了各粒级团聚体有机碳含量。免耕结合秸秆覆盖（NS）显著改善土壤容重且对各粒级团聚体有机碳含量提升幅度最大，是最佳处理。

关键词: 免耕, 覆膜, 秸秆覆盖, 有机碳, 团聚体, 黑垆土, 渭北旱塬

Abstract:

【Objective】The aim of this study was to clarify the effects of long-term no-tillage and mulching measures on soil aggregate structure and organic carbon content in Weibei dry plateau farmland, and to explore suitable tillage measures to improve the local soil.【Method】On the basis of continuous 16-year field positioning experiments, a total of 5 field management measures were selected as experiment treatments, including traditional tillage (CT), no-tillage and no mulch (NT), no-tillage + straw mulch (NS), no-tillage + plastic film mulching (NP), and no-tillage + straw + plastic film mulching (NSP). The 0-40 cm ring knife and profile soil samples were collected during the spring maize harvest in October 2019, and the bulk density, aggregate particle size distribution and organic carbon content were determined.【Result】(1) No-tillage and mulching measures (NT, NP, NS and NSP) affected the bulk density and aggregate size distribution of Heilu soil. No-tillage and mulching measures both increased the soil bulk density of the plough layer (0-20 cm), of which 0-10 cm increased significantly (6.8%-17.8%). The changes of bulk density and porosity of the plough layer were opposite to those of the plough layer. The proportion of micro-aggregates was significantly reduced, which promoted the transformation of micro-aggregates into macro-aggregates. The weight percentage of aggregates of each particle size in the plough layer (0-20 cm) was distributed as follows: larger aggregates (0.25-2 mm)>large aggregates (>2 mm)>micro aggregates (0.053-0.25 mm)>powder. The clay fraction (<0.053 mm), the larger aggregates and silty clay fractions in the plow bottom layer (20-40 cm) were significantly higher than the macroaggregates and microaggregates. (2) Under no-tillage and mulching measures, the organic carbon content increased with the increase of aggregate particle size. In the 0-40 cm soil layer, the organic carbon content of the aggregates of each particle size under NT treatment was significantly lower than that under CT treatment, while the NS and NSP treatments were significantly higher than those under CT treatment. (3) The particle size distribution of aggregates was the dominant factor causing the change of the nutrient contribution rate of aggregates. The total organic carbon accumulation in the plough layer was dominated by aggregates>0.25 mm, and the plough layer was mainly composed of silty clay components and organic carbon in larger aggregates. 【Conclusion】Long-term no-tillage and mulching measures promoted the transformation of micro-aggregates into macro-aggregates in the plough layer. Compared with traditional tillage, no-tillage and plastic film mulching decreased the organic carbon content of aggregates of various particle sizes in Heilong soil and in the plough layer, respectively. However, no-tillage mulching (NS, NP and NSP) increased the organic carbon content of aggregates of each particle size compared with no mulching. Straw mulching alone had the best effect, and significantly improved the bulk density and the organic carbon content of each particle size aggregate increased the most, which was the best treatment in this study.

Key words: no-tillage, coated, straw mulching, organic carbon, aggregate, Helu soil, Weibei dry plateau

周明星, 代子俊, 樊军, 付威, 郝明德. 免耕结合覆盖措施对渭北旱塬黑垆土结构与团聚体有机碳含量的影响[J]. 中国农业科学, 2023, 56(12): 2329-2340.

ZHOU MingXing, DAI ZiJun, FAN Jun, FU Wei, HAO MingDe. Effect of No-Tillage Combined with Mulching on the Structure and Organic Carbon Content of Aggregates in Heilu Soil of the Weibei Dry Plateau[J]. Scientia Agricultura Sinica, 2023, 56(12): 2329-2340.

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代码 Code	处理 Treatment	耕作管理 Tillage management
CT	传统耕作 Conventional tillage	仅在春玉米播种前翻耕一次，无覆盖 One plough before spring maize, no mulching on soil
NT	连年免耕 No tillage	试验期连年免耕，无覆盖 No-tillage and no mulching have been taken all the years
NS	NT+秸秆覆盖 NT + straw mulching	在NT的基础上，每季作物收获后，秸秆（约7 000 kg·hm^-2）粉碎成条状，均匀覆盖小区，播种时收拢放置于行间 Based on NT, all the harvested straw (7 000 kg·hm^-2) was crushed into strips and covered on each plot. Before maize seeding, all the straw was piled up in inter-rows
NP	NT+地膜覆盖 NT + plastic film mulching	在NT的基础上，垄上覆膜，行间不覆膜，膜上打孔种植 Based on NT, only the ridges covered with plastic films, leave inter-rows clear
NSP	NT+秸秆覆盖+地膜覆盖 NT + straw mulching + plastic film mulching	在NT基础上，秸秆覆盖同NS，地膜覆盖同NP Based on NT, straw mulching was the same as NS, and plastic film mulching was the same as NP

处理 Treatment	容重 Soil bulk density (g·cm^-3)
处理 Treatment	0-10 cm	10-20 cm	20-30 cm	30-40 cm
CT	1.12±0.09cC	1.36±0.03aB	1.55±0.07aA	1.57±0.08aA
NT	1.28±0.07aB	1.36±0.05aAB	1.39±0.09bA	1.40±0.05cA
NP	1.32±0.05aB	1.40±0.06aA	1.45±0.07bA	1.15±0.04bcA
NS	1.20±0.05bC	1.40±0.05aB	1.45±0.06bAB	1.50±0.08abA
NSP	1.25±0.03abC	1.40±0.06aB	1.39±0.03bB	1.55±0.06aA

处理 Treatment	总有机碳含量 Total organic carbon content (g·kg^-1)
处理 Treatment	0-10 cm	10-20 cm	20-30 cm	30-40 cm
CT	16.30±0.69c	11.21±0.65c	9.33±0.44c	8.54±0.32b
NT	13.53±0.56e	10.00±0.66bc	9.26±0.56c	8.29±0.42b
NP	14.91±0.89d	11.18±0.45bc	10.41±043b	8.96±0.44ab
NS	20.35±1.53a	13.47±0.35a	10.93±0.35ab	10.20±0.56a
NSP	18.08±0.89b	12.57±0.25ab	9.33±0.44c	9.40±0.42ab