Plow Tillage Research Articles

Contribution of wheat and maize to soil organic carbon in a wheat‐maize cropping system: A field and laboratory study

Abstract Retention of crop biomass is widely recommended to improve soil organic carbon (SOC). However, the magnitude of contribution of above‐ground residues and below‐ground roots from C3 and C4 crops to SOC is unclear. Data from a 10‐year field experiment and a 60‐day laboratory incubation were synthesized to identify the respective contribution of C3 (e.g., wheat) and C4 (e.g., maize) residues and roots to SOC, as well as its underlying mechanisms under no‐till (NT) using 13C labelling trace in wheat‐maize rotations. The field experiment showed that residue retention significantly increased SOC accumulation, and SOC derived from wheat was 126.0% higher than that from maize. Conversion to NT promoted SOC derived from wheat and thus accumulated 17.6% higher SOC stock compared with plough tillage (PT) under residue returning at 0–20 cm soil depth (p < 0.05). The data from laboratory incubation revealed the mechanisms that lower priming effects at 0–10 cm depth decreased total mineralization by 91.8% after inputs of wheat residues and roots compared with that of maize residues and roots, especially under NT compared with PT. Priming effects were negatively correlated with enzyme activities associated with the C recycle, SOC, and total nitrogen (TN) contents (p < 0.01). NT increased enzyme activities, SOC, and TN contents and thus reduced priming effects and improved residual carbon. Synthesis and applications. These results suggested that wheat may contribute more to SOC accumulation than maize, and carbon increment efficiency in farmland could be enhanced by considering the crucial roles of C3 crops in SOC accumulation. NT practice sustains the benefits of C3 crops to SOC sequestration in the upper soil depths.

Better tillage selection before ridge—furrow film mulch can facilitate root proliferation, and increase nitrogen accumulation, translocation and grain yield of maize in a semiarid area

Plastic film mulch systems are used widely in arid areas, and the associated tillage measures affect soil properties, root and crop growth, and nutrient uptake. However, much debate surrounds the most suitable tillage method for plastic film mulch systems. We conducted a two-year field experiment to explore the impact of three tillage treatments - rotary tillage before ridge–furrow plastic film mulch (MR), no-tillage before ridge–furrow plastic film mulch (MZ), and plow tillage before ridge–furrow plastic film mulch (MP) - on soil total nitrogen, available nitrogen, root stratification structure, nitrogen transfer and utilization, and maize yield. The results showed that MP had better soil quality than either MR or MZ over 2019 and 2020, with higher nitrate-nitrogen and total nitrogen in the 0–40 cm soil layer. MP improved the soil physicochemical properties more than the other treatments, producing significantly higher root numbers and root biomass for the aerial and underground nodal roots than MR and MZ. At harvest, MP had the highest root biomass density, root length density, and root surface area density in the different soil layers (0–20, 20–40, and 0–40 cm). Significant correlations occurred between root biomass and aboveground nitrogen accumulation during maize growth. During grain filling, MP had the greatest nitrogen transfer amount, significantly increasing root and aboveground nitrogen transfer by 19.63–45.82% and 11.15–24.56%, respectively, relative to the other treatments. MP significantly produced 1.36–26.73% higher grain yields and a higher grain crude protein content at harvest than MR and MZ. MP also had higher values for the nitrogen harvest index, nitrogen uptake efficiency, and partial factor productivity of nitrogen fertilizer than MR and MZ. In conclusion, plow tillage combined with a ridge–furrow plastic film mulch system facilitated maize root development and improved nitrogen utilization, thereby increasing maize yield more than the other treatments.

Patterns of denitrifier communities assembly and co-occurrence network regulate N2O emissions in soils with long-term contrasting tillage histories

Denitrification is reducing nitrate to nitrous oxide (N2O) and nitrogen (N2) under the action of denitrifying microorganisms, which are the main source of soil N2O emissions. However, the co-occurrence pattern and community assembly process of denitrifier communities have not been studied in agricultural soils with long-term contrasting tillage histories. Based on a continuous (> 11 yr) conservation experiment, we aimed to understand the community assembly process and co-occurrence network of nirK-, nirS-, nosZI- and nosZII-type denitrifier communities under conservation tillage (i.e., zero tillage (ZT) and chisel plough tillage (CPT)) and conventional tillage (i.e., plow tillage (PT)). Continuous in situ measurements showed that long-term conservation tillage significantly decreased the denitrification potential and N2O emission fluxes. CPT and ZT significantly increased the taxonomic and phylogenetic diversity of nirK, nosZI, and nosZII type communities, whereas consistently decreased the diversity of nirS-type communities, compared with PT. Although the assembly of nirK, nirS, nosZI, and nosZII type denitrifier communities were dominated by stochastic processes, the relative importance of stochastic assembly of denitrifying microbial communities was higher in conservation tillage soil. The co-occurrence network analyses further revealed clear tillage-induced ecological functions of N2O emissions, as evidenced by lower key nodes abundance and robustness of nirS and nirK communities network and higher key nodes abundance and robustness of nosZI and nosZII communities in conservation tillage soils. Variation partitioning analysis further indicated that the assembly processes significantly changed soil N2O emission intensity by regulating α-diversity and the key species abundances in the co-occurrence network of denitrifying communities. Overall, conservation tillage practices increased the diversity and the key nodes abundance of nosZI- and nosZII-type communities and decreased the diversity and the key nodes abundance of nirS- and nirK-type communities by regulating the relative importance of the stochastic assembly process of denitrifier communities, which is eventually likely to curb N2O emissions by strengthening the capacity of the N2O sink and weakening the capacity of the N2O source. These findings provide new insights into the formation of dryland microbial communities in agricultural soils with long-term contrasting tillage histories. Especially considering future climate change, this knowledge would prove useful in improving agroecosystem productivity and curbing greenhouse gas emissions.

Impact of Tillage and Straw Treatment Methods on Rice Growth and Yields in a Rice–Ratoon Rice Cropping System

The rice–ratoon rice cropping system has the advantages of saving labor and imparting economic benefits. Optimizing tillage and straw management is beneficial for improving ratoon rice growth and yield. In this study, field experiments were conducted to examine the effects of four tillage and straw managements on the growth and yield of a rice–ratoon rice cropping system in central China in 2020 to 2021. The managements included no-till with main-season and ratoon-season rice residues retained on the soil’s surface (NT+S), plow tillage with residue retention (CT+S), no-till with residues removed (NT-S), and plow tillage with residues removed (CT-S). Compared to NT, CT significantly increased yield by 33.70% and 29.12% in the main and ratoon seasons, respectively. Compared to straw removal, straw returning significantly increased yield by 13.37% and 27.29% in the main and ratoon seasons, respectively. In general, both CT and straw returning improved root function (root activity and root dry weight) and photosynthetic capacity (leaf area index, net photosynthetic rate, and leaf chlorophyll content). CT combined with straw returning was able to achieve the highest annual rice yield.

Interlinkages between soil properties and keystone taxa under different tillage practices on the North China Plain

Revealing the role of keystone taxa in maintaining community structure and driving soil properties is crucial for estimating agri-soil quality and microbial function. However, it is still unclear that how tillage practices mediated the associations between keystone taxa and soil properties to affect soil quality. Hence, this study aimed to investigate the influences of no tillage (NT), conventional tillage (CT), and plow tillage (PT) on soil microbial community structure, co-occurrence pattern, and keystone taxa, as well as the correlations between keystone taxa and soil properties. Compared with NT, CT and PT exhibited lower soil organic carbon (SOC), bulk density (BD), and mean weight diameter, as well as higher cumulative carbon mineralization (Cm). Bacterial diversity and richness were decreased under PT. A total of 58 keystone taxa were identified in the co-occurrence network and 35 genera were significantly separated by tillage practices. Most cellulolytic, chitinolytic, and nitrobacterium genera involved in decomposing complex soil organic matter were abundant under PT. Soil quality index (SQI) of the three tillage practices were in the following order: NT > CT > PT, while the Cm and SOC had greater communalities in SQI. Structural equation model (SEM) further indicated that tillage practices affected soil quality by mediating bacterial diversity and keystone taxa. Additionally, network analysis and SEM indicated that keystone taxa were significantly driven by SOC, Cm, and BD. Overall, the study findings suggested that keystone taxa might serve as biomarkers of agri-soil quality, and healthy farmland ecosystems might be obtained by targeting these species.

Land Use, Productivity, and Profitability of Traditional Rice–Wheat System Could be Improved by Conservation Agriculture

Power tiller-driven plow tillage and crop residue exclusionary Traditional Agriculture practices are expensive, labor-demanding, soil damage, and eco-unfriendly. Over the last several years, pursuits of crop production through sustaining the productive capacity of soils, and environmental quality, have raised concern to adopt Conservation Agriculture worldwide. Single tillage combined with herbicides and crop residue retention principles of Conservation Agriculture is being developed. Between 2016–2017 and 2017–2018, a two-year on-farm experiment was done in Bangladesh. We practiced two crop establishment methods; Traditional Agriculture: Plow tillage followed by three manual weeding without residue preservation of previous crop and Conservation Agriculture: Pre-plant herbicide + single tillage + pre-emergence herbicide + post-emergence herbicide; under rice–wheat and rice–wheat–mungbean systems. Data reveal that Conservation Agriculture was a more cost-effective crop establishment technique than Traditional Agriculture in rice, wheat, and mungbean by increasing the ratio of benefit to costs by 24.3%, 35.7% and 48.8%, respectively, with savings in tillage operations (66.3%, 58.1%, and 57.6%, respectively), weeding expenditures (59.2%, 24.5%, and 42.2%, respectively), and manpower requirements (25.1%, 27.2%, and 31.3%, respectively). This has resulted in an increase of 32% productivity of rice–wheat–mungbean systems with the yield advantage of 16%, 31% and 37% in rice, wheat and mungbean, respectively. When mungbean was added, the rice–wheat system’s productivity rose by 43%. The rice–wheat–mungbean system under Traditional Agriculture had the highest land utilization efficiency (99.45%), followed by Conservation Agriculture (92.05%), which expanded the scope to include additional crops in the rice–wheat–mungbean system. Moreover, Conservation Agriculture had a 59.7% greater production efficiency than Traditional Agriculture, where the rice–wheat–mungbean system having the highest production efficiency (53.00 kg–1 ha–1 day–1), followed by the rice–wheat system (45.57 kg–1 ha–1 day–1).

Nitrite oxidizing bacteria, Nitrobacter and Nitrospira, are differently influenced by season, fertilizer, and tillage in long-term maize culture

Nitrite (NO2−) oxidation is the second step in nitrification, following ammonia (NH3) oxidation, and catalyzed by nitrite oxidizing bacteria (NOB). Their activity is critical in preventing toxic accumulation of NO2−. The two major NOB genera in soil are Nitrobacter and Nitrospira. This study investigated how N fertilization and tillage management influenced these two NOB communities in long-term (>40 years) maize (Zea mays L.) cropping. To evaluate NOB community changes we used PCR and denaturing gradient gel electrophoresis (DGGE) to analyze Nitrobacter and Nitrospira NO2− oxidoreductase genes (nxr). Season, fertilizer rate, and tillage all influenced Nitrobacter and Nitrospira communities, but differentially for the two genera. Nitrobacter was more diverse in summer, whereas Nitrospira was more diverse in winter. Nitrobacter was more diverse in N-fertilized samples, whereas Nitrospira diversity decreased with increasing fertilizer rate in winter but not summer. Nitrobacter diversity was not significantly influenced by tillage, whereas no-tillage samples had more diverse Nitrospira, compared to plow tillage samples. In addition to providing evidence for better understanding the relationship between soil management and NOB communities, this study also helped to suggest linkages between ammonia oxidizing bacteria and Nitrobacter and between ammonia oxidizing archaea and Nitrospira that may facilitate future studies concerning ammonia-oxidizing nitrifiers and NOB.

Nitrate losses and nitrous oxide emissions under contrasting tillage and cover crop management

Agroecosystems in the upper Mississippi River Basin are highly productive but often contribute to deterioration of water quality and greenhouse gas emissions. Cover cropping and no-till are conservation strategies implemented to reduce the environmental impact of these agroecosystems. However, using multiple strategies can lead to systemwide interactions that are not fully understood. These interactions can affect not only environmental quality metrics, such as subsurface drainage nitrate losses or nitrous oxide (N2 O) emissions, but also may influence crop production potential. A field trial was initiated comparing nitrate losses, N2 O emissions, and crop production under systems with fall chisel plow tillage, fall chisel plow tillage with an oat (Avena sativa L.) cover crop (CP-oat), no-till (NT), no-till with a rye (Secale cereale L.) cover crop (NT-rye), and NT with zero N fertilizer. Pathways for nitrate losses and N2 O emissions did not appear linked and were not tied to cover crop or tillage practices. Nitrate losses were linked with drainage volumes, and cover crops and tillage had limited effect on cumulative drainage volumes. Notably, NT-rye altered the relationship between drainage volume and nitrate losses by reducing nitrate concentrations, lowering nitrate losses by 59 ±9% compared with CP-oat and 67 ± 9% compared with NT. Neither cover crop nor tillage consistently affected N2 O emissions or crop yield. Rather, N2 O emissions were closely tied with fertilizer N application and seasonal weather patterns. These findings indicate that nitrate leaching and N2 O emissions are regulated by separate mechanisms, so conservation management may require stacking multiple practices to be effective.

Soil properties and microbial communities of spring maize filed in response to tillage with straw incorporation and nitrogen fertilization in northeast China.

Soil enzymes and microorganisms are both important to maintaining good soil quality and are also sensitive to changes in agricultural management. The individual effects of tillage, straw incorporation and nitrogen (N) fertilization on soil enzymes and microflora have been widely acknowledged, but their interactive effect remains largely unknown. In a 5–year in–situ field study, effects of rotary (RTS) and plow tillage (PTS) practices with straw incorporation combined with three N fertilization levels (0 kg N ha–1, CK; 187 kg N ha–1, MN; 337 kg N ha–1, HN) on soil enzyme activities and microbial communities were assessed. Our results showed that the activities of β–glucosidase (βG), N–acetylglucosaminidase (NAG) and acid phosphatase (APH) were improved in RTS+MN. The bacterial and fungal abundances in RTS+MN and RTS+HN were 1.27–27.51 times higher than those in other treatment groups. However, the bacterial and fungal alpha diversities were enhanced in PTS+MN and PTS+CK compared with other treatments, respectively. Proteobacteria and Basidiomycota were the predominant phylum for the respective bacterial and fungal communities. Moreover, significant interactive effects were found in the fungal community composition, but only minor impacts were observed on the bacterial community composition. Soil water content and penetration resistance contributed more to the soil enzyme activity and microbial community than other soil properties investigated, whereas there was a significant positive correlation between βG and APH activities and microbial abundance. These findings can provide new insights into tillage with straw incorporation and N fertilization on maize cultivation in northeast China.

Increased Resilience of Peas Toward Root Rot Pathogens Can Be Predicted by the Nematode Metabolic Footprint

Legumes are important drivers of soil fertility, however, their frequent use in rotations fosters long-lived soil-borne pathogens that can seriously compromise legume root health and nitrogen fixation. To overcome this, the current study aims at improving the general soil suppressiveness toward pests and diseases by agroecosystem management that can be predicted by nematode-based bioindicators. Two long-term organically managed agroecosystems comparing plow and shallow non-inversion tillage were analyzed for free-living nematode communities. Soils out of these agroecosystems were evaluated further in a greenhouse assay for their ability to suppress pea root rot caused by Didymella pinodella, Fusarium avenaceum, and F. redolens. There was a general trend for higher levels of pea root rot disease severity following inoculations with single pathogens, however, this effect was heterogeneous among experiments and tillage systems. This was mainly due to an already very high resident population of D. pinodella in soil and the presence of seed-borne F. oxysporum determined by their high incidence in pea roots irrespective of the soil and inoculated pathogens. Additional inoculation with D. pinodella, for example, resulted in only 8.5% biomass reduction compared to the non-inoculated control, in both tillage systems. Similar biomass losses were recorded in non-inversion tilled soils inoculated with F. redolens. When analyzed across inoculation treatments, the pea root rot disease severity was only slightly reduced in non-inversion tilled soils when compared to the plough systems (11% in Exp 1 and, 9% in Exp 2), however in both experiments non-inversion tillage resulted in greater pea biomass (33 and 19% in Exp1 and 2, respectively). Furthermore, the metabolic, enrichment, and bacterivore carbon footprints of nematodes were 88, 81, and 97% higher, respectively, in the non-inversion tilled soils compared to the plough. The metabolic carbon footprint of nematodes correlated negatively with pea root rot disease severity (rho = −0.71, p = 0.047). Hence, non-inversion tillage was effective in controlling pea root rot. The use of nematode metabolic footprints for predicting soil health should be extended for various agroecosystems aiming for its general use in evaluating effects of agroecosystem management through researchers and potentially farm management advisors.

Sensitivities of Physical and Chemical Attributes of Soil Quality to Different Tillage Management

Tillage management is a direct factor in affecting soil quality, which is a key factor in sustainable agriculture. However soil quality evaluation needs significant manpower, material resources and time. To explore the sensitive indicators of soil quality affected by tillage management, eight soil physical and chemical properties under three tillage managements, including plow tillage, subsoiling tillage and rotary tillage, were determined under a long-term experiment in North China Plain. The results showed that subsoiling tillage management had the highest soil organic carbon and total nitrogen in the 0–20 cm layer and the lowest soil bulk density in the 30–40 cm layer. Rotary tillage management had the highest soil water content in the 0–40 cm layer. Meanwhile, compared to 2002, the soil organic carbon, total nitrogen and soil bulk density had varied greatly in 2012, but there was no significant difference between 2012 and 2018. However, other property concentrations tended to increase in 2002, 2012 and 2018. In addition, there was a significant linear relationship between soil quality index and grain yield. Subsoiling tillage management had the highest soil quality index and gain yield both in 2012 and 2018. The soil quality can be evaluated through the sensitive indicator of soil organic carbon, total nitrogen, soil bulk density, total phosphorus and soil water content, which provides a scientific basis for selecting reasonable tillage management and evaluating soil quality in this agricultural production area or other similar areas.

Improved soil structural stability under no-tillage is related to increased soil carbon in rice paddies: Evidence from literature review and field experiment

Improving soil structural stability (SSS) and soil organic carbon (SOC) are critical for soil health and environmental pollution mitigation. No-tillage alters many soil properties (e.g., SOC), however, its effects on SSS in rice paddies are unclear. Therefore, we used field experiment and meta-analysis to determine the effects of no-tillage on wet stability of aggregates (WSA), clay dispersibility (ClayDis), mean weight diameter (MWD), and aggregate SOC distribution and mineralization in rice paddies. The field experiment included four tillage practices: no-tillage, rotary tillage and moldboard plow tillage with rice straw retention (NTS, RTS and CTS respectively), and moldboard plow tillage with rice straw removal (CT). The WSA at 0–5 cm soil depth was significantly higher under NTS compared with CTS. The ClayDis at 5–10 cm soil depth under NTS was 36% lower ( P < 0.05) than CTS. The relationship between SOC and WSA fits a broken stick model, with an inflection point of clay/SOC ratio at 12.5. Higher SOC under no-tillage might result from the protection of >2 mm aggregates (macroaggregates) and lower SOC mineralization of < 2 mm aggregates. Additionally, the meta-analysis showed that no-tillage increased ( P < 0.05) the macroaggregate content, WSA and MWD. However, the current research regarding tillage effects on paddy ClayDis is insufficient. In rice paddies, the increased macroaggregate content may contribute to increasing SOC, which improves SSS under no-tillage. • No-tillage in rice cropping increased soil structural stability. • Aggregate stability increases with SOC content and its mineralization. • SOC mineralizability of <2 mm aggregates was low under no-tillage. • No-tillage increased SOC storage in >2 mm aggregates. • Carbon mineralization did not differ among aggregate size classes.

Effect of Catch Crops and Tillage Systems on the Content of Selected Nutrients in Spring Wheat Grain

This paper presents the effects of catch crops (white mustard, lacy phacelia, and a mixture of legumes—faba bean + spring vetch) and two tillage systems (plough tillage and no-tillage) on some quality parameters of spring wheat grain. A field experiment in growing spring wheat in monoculture was conducted in the period 2016–2018 in Czesławice (central part of the Lublin region, Poland). An assumption was made that the nutritional composition of wheat grain could be influenced already at the stage of selection of agronomic practices by modifying the soil chemical and enzyme composition—being the “starting point” for grain quality. It was proven that all the catch crops tested in this study contributed to an improvement in the chemical composition of the soil used in the experiment (a significant increase in humus, P and Mg content). Both the catch crops and the conservation (no-tillage) system stimulated the activity of soil enzymes: dehydrogenase and urease. This resulted in more favorable soil conditions for spring wheat grown in monoculture. The cultivation of the catch crops (particularly white mustard) indirectly contributed to an increased content of dietary fiber and o-dihydroxyphenols in wheat grain. Moreover, the content of most of the amino acids determined and the essential amino acid index (EAAI) in wheat grain were found to be more favorable in the treatments with the catch crops. The highest content of all the macro- and micronutrients analyzed in wheat grain was found in the catch crop treatments (especially that with white mustard). It should be noted that spring wheat responded favorably to the reduced tillage system (no-tillage). Since the grain content of o-dihydroxyphenols, magnesium, calcium, copper, manganese, iron, selenium, and some amino acids (especially essential ones: Lys, Met, Trp) was found to be higher compared to plough tillage.

No-Tillage Promotes Wheat Seedling Growth and Grain Yield Compared with Plow–Rotary Tillage in a Rice–Wheat Rotation in the High Rainfall Region in China

Optimizing soil properties to match ecological conditions can alleviate stress damage and promote crop growth. However, the suitable soil conditions for wheat growth in an integrated rice–wheat breeding scheme under high rainfall and the mechanisms that affect yield production are not well known. Field experiments were carried out at two sites, which were all located in Jiangsu Province, China, a subtropical monsoon climate zone during two wheat growing seasons, to assess the effects of plow tillage followed by rotary tillage (PR) and no-tillage (NT) on soil physical and chemical properties, wheat seedling growth, grain yield, and spike amounts and quality. The finding indicates that with the reduction in soil mixing, soil bulk density was higher in NT than in PR, which helped to maintain moisture in dry soil. In soils with high water content, in NT, when the wheat field was subjected to waterlogging stress, the drainage decreased to deeper soil possibly due to reduced infiltration and a higher evaporation of surface water. The diurnal variation in soil temperature decreased in NT, and when the soil was cold, NT helped to insulate soils at 0–25 cm. Compared with PR, the contents of available nitrogen and phosphorus increased at 0–20 cm in NT. Root biomass and root activity of wheat seedlings at 0–20 cm were also greater in NT than in PR. Compared with PR, wheat also had more culms at the beginning of the overwintering stage, more spikes, and higher grain yield in NT, but the differences were not significant under excessive soil moisture. Therefore, the soil hydrothermal environment and spatial distributions of nutrients in NT promoted shallow root growth and tiller development in the early phase of wheat growth, which led to higher amounts of spikes per plant that resulted in high-yielding wheat crops.

Straw Strip Return Increases Soil Organic Carbon Sequestration by Optimizing Organic and Humus Carbon in Aggregates of Mollisols in Northeast China

In agroecosystems, effective straw return modes are one of the key practices for increasing soil fertility and carbon (C) availability. Although they improve soil quality, there is currently little information available regarding the influence of distinct straw return modes with respect to potential soil organic carbon (SOC) sequestration. In this study, we established a five-year (2015–2019) field experiment in Mollisols of Northeast China, which included four straw return modes, plow tillage with straw return as the control (PTS), rotary tillage with straw return (RTS), rotary tillage with straw strip return (RSS), and plow tillage with straw strip return (PSS), to investigate the impact on soil physicochemical properties, aggregates, and C sequestration. The results reveal that RSS effectively improved the soil physicochemical properties. Such responses increased the contents of SOC, fulvic acid carbon (FAC), and humin carbon (HMC) in all soil layers (0–30 cm). The proportion of macroaggregates was higher in RSS, whereas the proportion of silt/clay was the lowest at depths of 0–20 cm; consequently, the mean weight diameter (MWD) and geometric mean diameter (GMD) of RSS were higher at depths of 0–20 cm due to the improved physical soil structure. In the 0–10 cm and 20–30 cm layers, the highest humic acid carbon (HAC) concentrations associated with all aggregate sizes were found for RSS, in contrast to 10–20 cm, which had increased HMC. Structural equation modeling (SEM) revealed that C transformation was mainly mediated through silt/clay-associated FAC, HMC, and SOC, ultimately determining HAC (81%) and HMC (85%) as the primary humus fractions for SOC sequestration. Therefore, this study shows that RSS is the suitable straw return mode for effectively improving soil quality, aggregate stability, and C sequestration in Mollisols of Northeast China.

Higher Profitability of WheatMungbean-Rice System Through Conservation Agriculture Practice in Sub-Tropical Climate of Bangladesh

Two-Wheel Tractor (2WT) operated plow tillage and crop residue exclusion practices in the rice-wheat system are costly, labor-intensive, soil destructive, and non-ecofriendly. In recent years, pursuits of healthy food production through sustaining the productive capacity of soils, and environmental quality, have raised concerns to adopt Conservation Agriculture (CA) worldwide. Single-Pass Tillage (SPT) combined with herbicides and crop residue retention principles of CA is being developed in Bangladesh. Between 2014 and 2016, we conducted a two-year on-farm experiment under the wheat-mungbean-rice system in Bangladesh. These crops were grown under two crop establishment methods; T1: Plow Tillage (PT) + three times manual weeding by hand, and T2: Pre-plant knockdown herbicide (PRE) + SPT + Pre-emergence herbicide (PE) + Post-emergence herbicide (PO). Treatments were combined with two levels of crop residues, R0: zero residues and R50: 50% anchored residue. The PT was accomplished with two primary tillage operations performed by a 2WT, whereas SPT was completed by a single-pass process using a Versatile Multi-crop Planter machine. The PRE: glyphosate, PE: pendimethalin for all crops, and PO: carfentrazone-ethyl+isoproturon, fenoxaprop-p-ethyl, and ethoxysulfuron-ethyl for wheat, mungbean, and rice, respectively, were applied at the prescribed dosage and time. Data reveal that, relative to traditional practice (PT+3HW without residue), the CA practice (PRE + SPT + PE + PO with 50% residue) resulted in 30, 39, and 15% higher yield and 37, 29, and 22% higher economic returns in wheat, mungbean, and rice, respectively. The productivity of the wheat-mungbean-rice system was 41% higher than that of the wheat-rice system.

Fenlong-Ridging Promotes Microbial Activity in Sugarcane: A Soil and Root Metabarcoding Survey

Fenlong-ridging (FL) is a recently proposed conservation tillage technology which has dramatic differences to traditional ones. Previous studies have demonstrated in many crops that FL has yield-increasing effects without additional inputs. However, little is known about the role that microbes play in mediating the growth-promoting effects of FL, which restricts its further application and improvement. Here, we characterized variation in the soil and root microbial diversity of sugarcane (GT44) under FL and traditional turn-over plough tillage (CK) by conducting 16S rRNA and ITS metabarcoding surveys. We also measured several phenotypic traits to determine sugarcane yields and analyzed the chemical properties of soil. We found that: (i) plant height (PH) and total biomass weight (TW) of sugarcane plants were 9.1% and 21.7% greater under FL than those under CK, indicating\increased biomass yield of the sugarcane in FL operation; (ii) contents of organic matter, total nitrogen, available phosphorus, and available potassium were lower in soil under FL than those under CK, which indicates the utilization of soil nutrients was greater in FL soil; (iii) FL promoted the activity of endophytic microbes in the roots, and these diverse microbial taxa might have an effect on sugarcane yield and soil chemical properties; and (iv) Sphingomonas, Rhizobium, and Paraburkholderia and Talaromyces, Didymella, and Fusarium were the top three most abundant genera of bacteria and fungi, respectively, in soil and root samples. In addition, strains from Rhizobium and Talaromyces were isolated to verify the results of the metabarcoding survey. Overall, our study provides new insights into the role of microbes in mediating the growth-promoting effects of FL. These findings could be used to further improve applications of this novel conservation tillage technology.

Assessing synergistic effects of crop rotation pattern, tillage practice, and rhizosphere effect on soil bacterial community structure and assembly in China's Loess Plateau farmlands

Soil bacterial communities are important soil regulators in agroecosystems. However, few studies have investigated the influences of integrated agricultural management practices on farmland soil bacterial community diversity and assembly processes. In this study, we assessed the impact of crop species (maize and soybean), tillage practice (chisel plow tillage, CPT; zero tillage, ZT; plow tillage, PT), rhizosphere effect (rhizosphere and bulk soils), and their interactions on the soil bacterial communities in Loess Plateau farmlands. Conservation tillage significantly increased soil moisture (SM), clay and sand fractions, and carbon and nitrogen levels; whereas silt fraction and pH decreased. Rhizosphere effect significantly improved soil texture and decreased SM, pH, total nitrogen, and nitrate nitrogen. Soybean cultivation significantly increased SM, silt fraction, and pH; while clay fraction decreased. Additionally, the rhizosphere effect decreased the competition among rhizosphere bacterial communities (edges: rhizosphere = 926, bulk = 1095; density: rhizosphere = 0.157, bulk = 0.184) and increased the structural complexity of the community network (modularity: rhizosphere = 0.857, bulk = 0.556); moreover, conservation tillage and soybean cultivation increased community network complexity (modularity: CPT = 0.879, ZT = 0.742, PT = 0.495; maize = 0.525, soybean = 0.888). Although the phylogenetic clustering of rhizosphere bacterial communities caused by the rhizosphere effect was lower than that of bulk soil bacterial communities (2.13%), it had no significant influence on rhizosphere or bulk soil bacterial community assembly, and deterministic processes dominated the formation of soil bacterial community structure. In conclusion, clarifying the variations in soil bacterial communities under integrated agricultural management practices can help predict trends in soil bacterial community function which can, in turn, effectively guide biological management decision-making in farming operations. Our findings may provide additional insights into the underground processes in farmland and facilitate the development of conservation farming operations as sustainable agricultural practices.

Improvement of Gear Durability for an 86 kW Class Agricultural Tractor Transmission by Material Selection

This study was conducted to ensure gear durability and design optimal transmission of agricultural tractors. A field test was conducted using an 86 kW agricultural tractor for plow and rotary tillage, which are typical agricultural operations. The field test was completed after about 107 h due to transmission noise and operational problems. As a result of disassembling the transmission, it was found that the range shift A and B gears were damaged. In the case of the range shift A gear, it was judged that plastic deformation occurred due to low contact stress, and the bending stress was low, therefore gear tooth breakage occurred in the range shift B gear. In order to ensure the durability of the transmission, four materials of alloy steel for machine structural use, such as SCr420, SNCM220, SCM822, and SNC815, were selected, and the safety factor and service life according to the gear materials were compared using simulation software. As a result of simulation analysis, SCM822 satisfied the target life value and was selected as a material for change. The damaged range shift A and B gears were changed to SCM822, and an axle dynamometer test was performed for the verification of the modified transmission. After conducting the axle dynamometer test, the transmission was disassembled, and it was confirmed that the range shift A and B gears were in normal condition. Therefore, it was considered that the durability of the transmission was ensured by satisfying the target life requirements of the gears. In the future, the transmission simulation model for 86 kW class agricultural tractor is expected to be utilized for the development of tractor transmissions, cost reduction, and optimal design.

Optimizing residue and tillage management practices to improve soil carbon sequestration in a wheat–peanut rotation system

The sustainable development of agriculture has been challenged by the decline of soil quality and the change of climate. It is well known that soil carbon (C) sequestration plays crucial roles in improving soil structural stability, mitigating greenhouse emissions, and promoting plant nutrient supply. Therefore, a 3-year field experiment was conducted to evaluate the effects of different residue and tillage management practices on soil C sequestration in a wheat–peanut rotation system. Four treatments were studied: moldboard plow tillage with wheat residue returning (PTS), rotary tillage with wheat residue returning (RTS), no tillage with wheat residue mulching (NTS), and no tillage with wheat residue removal (NT). Our results indicated that residue return favored the improvement of soil C sequestration capacity relative to residue removal. In addition, NTS improved soil C sequestration in the surface soil layer (0–5 cm), but markedly reduced soil C sequestration in the deeper soil layers (5–30 cm). NTS thus caused a more obvious soil stratification phenomenon, which was not conducive to improving soil quality. At the 5–30 cm soil depths, the soil labile organic C fractions concentrations, carbon pool management index (CPMI), macroaggregates-associated C storage, intra-aggregate C fractions concentrations, and soil total organic carbon (TOC) storage under PTS were all higher than those under other treatments. Overall, a peanut strategic cultivation management mode that combines moldboard plow tillage and wheat residue return may be used as a reference for optimizing agricultural soil management to achieve the improvement of soil C sequestration capacity in a wheat–peanut rotation system.