Conservation tillage: a way to improve yield and soil properties and decrease global warming potential in spring wheat agroecosystems

Abstract

Climate change is one of the main challenges, and it poses a tough challenge to the agriculture industry globally. Additionally, greenhouse gas (GHG) emissions are the main contributor to climate change; however, croplands are a prominent source of GHG emissions. Yet this complex challenge can be mitigated through climate-smart agricultural practices. Conservation tillage is commonly known to preserve soil and mitigate environmental change by reducing GHG emissions. Nonetheless, there is still a paucity of information on the influences of conservation tillage on wheat yield, soil properties, and GHG flux, particularly in the semi-arid Dingxi belt. Hence, in order to fill this gap, different tillage systems, namely conventional tillage (CT) control, straw incorporation with conventional tillage (CTS), no-tillage (NT), and stubble return with no-tillage (NTS), were laid at Dingxi, Gansu province of China, under a randomized complete block design with three replications to examine their impacts on yield, soil properties, and GHG fluxes. Results depicted that different conservative tillage systems (CTS, NTS, and NT) significantly (p < 0.05) increased the plant height, number of spikes per plant, seed number per meter square, root yield, aboveground biomass yield, thousand-grain weight, grain yield, and dry matter yield compared with CT. Moreover, these conservation tillage systems notably improved the soil properties (soil gravimetric water content, water-filled pore space, water storage, porosity, aggregates, saturated hydraulic conductivity, organic carbon, light fraction organic carbon, carbon storage, microbial biomass carbon, total nitrogen, available nitrogen storage, microbial biomass nitrogen, total phosphorous, available phosphorous, total potassium, available potassium, microbial counts, urease, alkaline phosphatase, invertase, cellulase, and catalase) while decreasing the soil temperature and bulk density over CT. However, CTS, NTS, and NT had non-significant effects on ECe, pH, and stoichiometric properties (C:N ratio, C:P ratio, and N:P ratio). Additionally, conservation-based tillage regimes NTS, NT, and CTS significantly (p < 0.05) reduced the emission and net global warming potential of greenhouse gases (carbon dioxide, methane, and nitrous oxide) by 23.44, 19.57, and 16.54%, respectively, and decreased the greenhouse gas intensity by 23.20, 29.96, and 18.72%, respectively, over CT. We conclude that NTS is the best approach to increasing yield, soil and water conservation, resilience, and mitigation of agroecosystem capacity.

Keywords: carbon sequestration; climate-smart agriculture; global warming; greenhouse gases; nutrients; sustainable conservation tillage; yield.

Figure 1

The geographical map of the experimental research site in Dingxi County, Gansu Province, China. ArcGIS 10.2 software was applied for production. The basic geographic information data come from the resource and environmental science and data center (http://www.resdc.cn/).

Figure 2

Climatic conditions of the study region in 2021. (A) The monthly average rainfall and (B) the monthly average temperature.

Figure 3

Properties of soil under conservative tillage systems in 2021 at 0–10 cm soil depth. (A) The soil gravimetric water content influenced by conservation tillage technique; (B) the water-filled pore spaces under conservation tillage; (C) the soil water storage affected by tillage practices; and (D) the soil temperature affected by tillage measures. Vertical error bars denote the corresponding standard error of mean values; n = 3. Significant differences were determined by a Duncan’s test.

Figure 4

Principal component analysis of spring wheat agronomic attributes and soil properties (physical, chemical, and biological).

Figure 5

Heat map correlation study of wheat agronomic traits and soil physical, chemical, and biological properties. Indicates significance at: *p < 0.05, **p < 0.010, and ***p < 0.0010. Note: the abbreviated words stand for SWC = soil gravimetric water content; WFPS = water-filled pore space; SWS = soil water storage; ST = soil temperature; BD = soil bulk density; P = soil porosity; Ks = soil saturated hydraulic conductivity; SOC = soil organic carbon; LFOC = light fraction organic carbon; SC = carbon storage; TN = total nitrogen; AN = available nitrogen; NS = nitrogen storage; TP = total phosphorous; AP = available phosphorous; TK = total potassium; AK = available potassium; ECe = soil electrical conductivity; pH = soil pH; MC = soil microbial counts; MBC = microbial biomass carbon; MBN = microbial biomass nitrogen; RY = wheat root yield; ABY = wheat aboveground biomass yield; TSW = thousand seed weight; GY = wheat grain yield; DMY = dry matter yield; HI = harvest index.

Figure 6

Seasonal and average greenhouse gas emissions under tillage systems in spring-wheat agroecosystem in 2021. Error bars represent the corresponding standard error of mean values; n = 3. Different lower-case letters and ‘*’ indicate significant differences amongst different treatments at p < 0.05 (Duncan’s test performed for mean separation). Note: (A,B) is the seasonal and average ecosystem respiration as affected by the tillage treatments; (C,D) is the seasonal and average CH₄ flux under conservation tillage; (E,F) is the seasonal and average N₂O flux under tillage practices.

Figure 7

Global warming potential (GWP) of CO₂, CH₄ and N₂O and greenhouse gas intensity (GHGI) under tillage practices in spring-wheat agroecosystem in 2021. Error bars represent the corresponding standard error of mean values; n = 3. Different lower-case letters and ‘*’ indicate significant differences amongst different treatments at p < 0.05 (Duncan’s test performed for mean separation). Note: (A) is the GWP of carbon dioxide as affected by the tillage treatments; (B) is the GWP of CH₄ as influenced by the tillage system; (C) is the GWP of N₂O as affected by the different tillage techniques; (D) is the net-GWP under tillage measures and (E) is the GHGI under tillage practices.

Figure 8

Principal component analysis for evaluating the influence of environmental variables on greenhouse gas emissions under conservation tillage practices. (A) The PCA analysis of environmental variables with carbon dioxide emission; (B) the PCA analysis of environmental variables with methane emission; (C) the PCA analysis of environmental variables with nitrous oxide emission; and (D) the PCA analysis of environmental variables with net global warming under different tillage systems.