长期少免耕与氮肥减量对全膜双垄沟播玉米产量及碳排放的调控作用

doi:10.3864/j.issn.0578-1752.2021.23.011

摘要/Abstract

摘要：

【目的】明确氮肥减量条件下耕作方式对土壤呼吸、碳排放、作物产量的影响,揭示玉米生长与土壤碳排放的关系。【方法】于2018—2019年依托2012年布设于甘肃农业大学旱作农业综合实验站的耕作方式及氮肥减量长期定位试验。本试验以具有良好集雨抑蒸、增温保墒作用的全膜双垄沟播技术为前提,采取二因素裂区设计,主区为4种耕作方式：翻耕（T1）;旋耕（T2）;深松耕（T3）和免耕（T4）,副区处理为两个施氮水平：氮肥减量（N1：基施氮200 kg·hm^-2）和传统施氮（N2：基施200 kg·hm^-2+拔节期施100 kg·hm^-2）。研究不同处理的玉米生长、土壤呼吸速率特征、碳排放量和土壤有机碳含量的变化,分析碳排放效率（CEE）及净生态系统生产力（NEP）。【结果】（1）耕作方式及施氮水平显著影响全膜双垄沟播玉米的生长,耕作方式对干物质积累的影响主要在灌浆期和成熟期,免耕处理显著提高了该时期的干物质积累量、生长率和净同化速率,较其他耕作方式籽粒产量提高2%—15%;施氮水平在拔节期—开花期对干物质的影响较大,但同一耕作方式下N1与 N2水平的产量差异不显著。（2）土壤呼吸速率呈先升高后降低的单峰曲线,在大喇叭口期—开花期达到峰值,耕作方式对土壤呼吸、碳排放量及碳排放效率的影响大于施氮水平,免耕处理的土壤呼吸速率较旋耕、翻耕和深松耕分别降低了4.3%、12.9%和24.3%,总碳排放量降低了21.5%、13.4%和31.2%,碳排放效率提高26.5%—55.9%;免耕减施氮肥较其他处理碳排放总量降低489—1 917.5 kg·hm^-2,碳排放效率提高了20.1%—56.2%。（3）所有处理均表现为大气CO₂的“汇”,但免耕和减施氮肥表现出更强的碳汇效应,与传统翻耕相比,免耕处理0—5 cm土层有机碳含量增加了11.3%（P<0.05）,与传统施氮相比,氮肥减量水平下0—10 cm土层的有机碳含量提高了5.8%（P<0.05）。（4）全膜双垄沟播玉米碳排放效率与干物质积累量、生长率和净同化率呈显著正相关关系,玉米碳排放效率与土壤有机碳含量呈极显著负相关,其原因主要是耕作方式和氮肥减量促进了玉米光合能力,从而捕获更多CO₂,进而提高了玉米固碳能力。【结论】在472—491 mm的年降水条件下,免耕结合氮肥减量（基施氮200 kg·hm^-2）能提高玉米产量、土壤有机碳含量,降低碳排放总量,提高碳排放效率,是陇中黄土高原全膜双垄沟播玉米一项绿色增产技术,建议在生产中使用。

关键词: 玉米, 免耕, 减氮, 土壤呼吸, 碳平衡, 产量

Abstract:

【Objective】 The effects of tillage practices on soil respiration, carbon emission and crop yield under nitrogen reduction were clarified, and the relationship between maize growth and soil carbon emission was revealed.【Method】The long-term tillage practices and reduced fertilization experiment initiated in 2012 within two-year (2018-2019) was conducted at the Rainfed Agricultural Experimental Station of the Gansu Agricultural University in the Gansu province of northwestern China. This experiment is based on the technology of full-film double-ridge and furrow sowing maize with good effect of collecting rainfall and inhibiting evaporation and increasing temperature and soil moisture. The experiment adopted the split plot design, and the main plots were four tillage practices (conventional tillage, rotary tillage, subsoiling, and no-tillage) and the subplot were two nitrogen application levels (nitrogen reduction (200 kg·hm^-2) and conventional nitrogen application (300 kg·hm^-2)). Based on this experiment, the maize growth, soil respiration rate, carbon emission and soil organic carbon content, carbon emission efficiency (CEE) and net ecosystem productivity (NEP) were assessed.【Result】(1) Tillage practice and nitrogen application level significantly affected the growth of maize, and the effect of tillage practice on dry matter accumulation was mainly in the filling stage and maturity stage. No tillage treatment significantly improved the dry matter accumulation, growth rate and net assimilation rate at these stages, which increased grain yield by 2%-15% compared with other tillage practices; nitrogen application level had a greater effect on dry matter during jointing flowering stage, but the same effect was observed, and there was no significant difference in yield between N1 and N2 under the same tillage practice. (2) The soil respiration rate showed a single-peak curve that first increased and then decreased, reaching its peak in the big bell mouth-flowering period. The effects of tillage practices on soil respiration, carbon emissions and carbon emission efficiency were greater than the nitrogen levels. Compared with rotary tillage, tillage and subsoiling, no tillage decreased soil respiration rate by 4.3%, 12.9% and 24.3%, respectively, and total carbon emission decreased by 21.5%, 13.4% and 31.2%, respectively, while carbon emission efficiency increased by 26.5%-55.9%. Compared with other treatments, no tillage combined with nitrogen reduction reduced total nitrogen and carbon emission by 489-1917.5 kg·hm^-2, while the carbon emission efficiency increased by 20.1%-56.2%. (3) All treatments showed a “sink” of atmospheric CO₂, but no-tillage and reduced nitrogen fertilizer showed a stronger carbon sink effect. The organic carbon content in 0-5 cm soil layer was significantly increased by 11.3% (P<0.05) compared with conventional tillage; the organic carbon content in 0-10 cm soil layer was increased by 5.8% (P<0.05) compared with conventional tillage. (4) There was a significant positive correlation between the efficiency of carbon emissions and the accumulation of dry matter, the rate of growth and net assimilation rate, and a significant negative correlation between the efficiency of carbon emissions and the organic carbon of the soil. This was mainly because the cultivation practices and application of nitrogen promoted maize’s photosynthetic ability, obtained more CO₂, and enhanced maize’s capacity for carbon fixation. 【Conclusion】 Under the condition of 472-491 mm annual precipitation, no tillage combined with nitrogen reduction (200 kg·hm^-2) could improve maize yield, improve soil organic carbon content, reduce total carbon emission, and improve carbon emission efficiency. A green yield-increasing technology of full-film double-ridge and furrow sowing maize in the Loess Plateau of Longzhong was recommended to be used in production.

Key words: maize, no-tillage, nitrogen fertilizer reducing, soil respiration, carbon balance, yield

周永杰,谢军红,李玲玲,王林林,罗珠珠,王进斌. 长期少免耕与氮肥减量对全膜双垄沟播玉米产量及碳排放的调控作用[J]. 中国农业科学, 2021, 54(23): 5054-5067.

ZHOU YongJie,XIE JunHong,LI LingLing,WANG LinLin,LUO ZhuZhu,WANG JinBin. Effects of Long-Term Reduce/Zero Tillage and Nitrogen Fertilizer Reducing on Maize Yield and Soil Carbon Emission Under Fully Plastic Mulched Ridge-Furrow Planting System[J]. Scientia Agricultura Sinica, 2021, 54(23): 5054-5067.

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处理 Treatment	拔节期 Jointing stage	开花期 Flowering stage	灌浆期 Filling stage	成熟期 Maturity
T1	38.79a	194.43a	288.7ab	437.96ab
T2	36.08a	190.57a	281.02b	427.97b
T3	39.39a	187.36a	284.00ab	443.89ab
T4	35.85a	196.18a	307.33a	478.05a
N1	37.92a	182.67b	295.18a	445.64a
N2	37.75a	201.61a	285.33a	448.29a
T1N1	37.17ab	192.99ab	302.35a	439.61ab
T1N2	40.41ab	195.87ab	275.05a	436.31ab
T2N1	38.49ab	175.48b	284.33a	420.28b
T2N2	33.67b	205.66a	277.71a	435.65ab
T3N1	37.67ab	174.91b	289.00a	457.58ab
T3N2	41.10a	199.81ab	279.00a	430.20ab
T4N1	35.86ab	187.28ab	305.33a	465.09ab
T4N2	35.84ab	205.08a	309.33a	491.02a
T	ns	ns	*	*
N	ns	*	ns	ns
N×T	*	*	ns	*

处理 Treatment	出苗期—拔节期 Sowing to jointing stage	拔节期—开花期 Jointing to flowering stage		开花期—灌浆期 Flowering to filling stage		灌浆期—成熟期 Filling to maturity
处理 Treatment	CGR	CGR	NAR	CGR	NAR	CGR	NAR
T1	0.76a	4.45a	7.78a	4.28a	5.34a	3.18a	4.85a
T2	0.71a	4.41a	8.48a	4.11a	5.85a	3.13a	5.19a
T3	0.77a	4.23a	7.59a	4.39a	5.87a	3.4a	5.48a
T4	0.70a	4.58a	8.37a	5.05a	6.69a	3.63a	5.52a
N1	0.73a	4.15a	7.50b	5.11a	6.70a	3.20a	5.08a
N2	0.74a	4.68a	8.61a	3.81b	5.17b	3.47a	5.45a
T1N1	0.73ab	4.45ab	7.35b	4.97a	5.94a	2.92a	4.54a
T1N2	0.79ab	4.44ab	8.20ab	3.60a	4.74a	3.43a	5.16a
T2N1	0.75ab	3.91b	7.43b	4.95a	7.01a	2.89a	4.71a
T2N2	0.66b	4.91a	9.53a	3.28a	4.68a	3.37a	5.67a
T3N1	0.74ab	3.92b	7.24b	5.19a	6.85a	3.59a	5.64a
T3N2	0.81a	4.53ab	7.94ab	3.60a	4.90a	3.22a	5.33a
T4N1	0.70ab	4.32ab	7.97ab	5.36a	7.01a	3.40a	5.43a
T4N2	0.70ab	4.84a	8.77ab	4.74a	6.36a	3.86a	5.62a
T	ns	ns	ns	ns	ns	ns	ns
N	ns	*	*	*	*	ns	ns
N×T	*	*	*	ns	ns	ns	ns

处理 Treatment	土层 Soil layer			平均 Mean
处理 Treatment	0-5 cm	5-10 cm	10-30 cm	平均 Mean
T1	9.07b	9.50a	8.71a	8.90a
T2	9.23b	8.57a	8.57a	8.68a
T3	9.03b	9.19a	7.82a	8.25a
T4	10.09a	8.69a	8.30a	8.66a
N1	9.57a	9.29a	8.32a	8.69a
N2	9.14a	8.69a	8.38a	8.56a
T1N1	9.37b	10.28a	8.60ab	9.00a
T1N2	8.78b	8.73ab	8.82ab	8.80a
T2N1	9.00b	8.55b	8.19ab	8.38a
T2N2	9.46b	8.60b	8.96a	8.98a
T3N1	9.19b	9.19ab	8.23ab	8.55a
T3N2	8.87b	9.19ab	7.41b	7.95a
T4N1	10.73a	9.14ab	8.28ab	8.83a
T4N2	9.46b	8.23b	8.32ab	8.50a
T	*	ns	*	ns
N	ns	ns	ns	ns
N×T	*	*	*	ns

处理 Treatment	籽粒产量 Grain yield (kg·hm^-2)		碳排放总量 Total carbon emission (kg·hm^-2)		碳排放效率 Carbon emission efficiency (kg·kg^-1)
处理 Treatment	2018	2019	2018	2019	2018	2019
T1	11386b	9613b	6197b	4947ab	1.89b	1.99b
T2	12457a	9921b	5815bc	4396bc	2.14b	2.27b
T3	12505a	10094ab	7112a	5588a	1.76b	1.82b
T4	12750a	11036a	4993c	3750c	2.59a	2.99a
N1	12031b	10164a	5921a	4632a	2.10a	2.25a
N2	12517a	10168a	6137a	4709a	2.09a	2.28a
T1N1	11345c	9710b	5971abc	4705abcd	2.00bc	2.11c
T1N2	11427c	9515b	6423ab	5189abc	1.78c	1.87c
T2N1	12320abc	9882ab	5671bc	4298cde	2.17c	2.3bc
T2N2	12594ab	9959ab	5958abc	4494bcde	2.11abc	2.23bc
T3N1	11811bc	9780ab	7024ab	5551ab	1.68abc	1.77c
T3N2	13199a	10408ab	7201a	5625a	1.84c	1.87c
T4N1	12651ab	11283a	5018c	3973de	2.55ab	2.84ab
T4N2	12849ab	10790ab	4967c	3528e	2.63a	3.14a
T	*	*	**	**	**	**
N	*	ns	ns	ns	ns	ns
N×T	**	*	*	*	*	*

处理 Treatment	总生物量 Total biomass (kg·hm^-2)		NPP (kg·hm^-2)		Rm (kg·hm^-2)		NEP (kg·hm^-2)
处理 Treatment	2018	2019	2018	2019	2018	2019	2018	2019
T1	40301a	37511a	18136a	16880a	5361b	4279ab	12775a	12601b
T2	38691a	39487a	17411a	17769a	5030bc	3803bc	12381a	13967ab
T3	38855a	40643a	17485a	18289a	6152a	4833a	11333a	13456ab
T4	38922a	41337a	17515a	18601a	4319c	3244c	13196a	15358a
N1	39090a	39940a	17591a	17973a	5122a	4007a	12469a	13966a
N2	39295a	39549a	17683a	17797a	5309a	4073a	12307a	13724a
T1N1	40298a	38183a	18134a	17182a	5165abc	4070abcd	12969a	13112b
T1N2	40305a	36839a	18137a	16578a	5556ab	4488abc	12581a	12089b
T2N1	38207a	39801a	17193a	17911a	4906bc	3718cde	12288a	14192ab
T2N2	39175a	39173a	17629a	17628a	5154abc	3887bcde	12475a	13741ab
T3N1	38692a	41353a	17412a	18609a	6075ab	4801ab	11336a	13807ab
T3N2	39018a	39934a	17558a	17970a	6229a	4866a	11329a	13105ab
T4N1	39164a	40422a	17624a	18190a	4341c	3437de	13283a	14753ab
T4N2	38680a	42252a	17406a	19013a	4297c	3052e	13109a	15962a
T	ns	ns	ns	ns	**	**	ns	*
N	ns	ns	ns	ns	ns	ns	ns	ns
N×T	ns	ns	ns	ns	*	*	ns	*