SciCombinator

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Concept: No-till farming

9

One of the primary challenges of our time is to feed a growing and more demanding world population with reduced external inputs and minimal environmental impacts, all under more variable and extreme climate conditions in the future. Conservation agriculture represents a set of three crop management principles that has received strong international support to help address this challenge, with recent conservation agriculture efforts focusing on smallholder farming systems in sub-Saharan Africa and South Asia. However, conservation agriculture is highly debated, with respect to both its effects on crop yields and its applicability in different farming contexts. Here we conduct a global meta-analysis using 5,463 paired yield observations from 610 studies to compare no-till, the original and central concept of conservation agriculture, with conventional tillage practices across 48 crops and 63 countries. Overall, our results show that no-till reduces yields, yet this response is variable and under certain conditions no-till can produce equivalent or greater yields than conventional tillage. Importantly, when no-till is combined with the other two conservation agriculture principles of residue retention and crop rotation, its negative impacts are minimized. Moreover, no-till in combination with the other two principles significantly increases rainfed crop productivity in dry climates, suggesting that it may become an important climate-change adaptation strategy for ever-drier regions of the world. However, any expansion of conservation agriculture should be done with caution in these areas, as implementation of the other two principles is often challenging in resource-poor and vulnerable smallholder farming systems, thereby increasing the likelihood of yield losses rather than gains. Although farming systems are multifunctional, and environmental and socio-economic factors need to be considered, our analysis indicates that the potential contribution of no-till to the sustainable intensification of agriculture is more limited than often assumed.

Concepts: Agriculture, Climate, Sustainability, Food security, Sustainable agriculture, Crops, No-till farming, Tillage

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Changes in agricultural practices are considered a possible option to mitigate climate change. In particular, reducing or suppressing tillage (no-till) may have the potential to sequester carbon in soils, which could help slow global warming. On the other hand, such practices also have a direct effect on regional climate by altering the physical properties of the land surface. These biogeophysical effects, however, are still poorly known. Here we show that no-till management increases the surface albedo of croplands in summer and that the resulting cooling effect is amplified during hot extremes, thus attenuating peak temperatures reached during heat waves. Using a regional climate model accounting for the observed effects of no-till farming on surface albedo, as well as possible reductions in soil evaporation, we investigate the potential consequences of a full conversion to no-till agriculture in Europe. We find that the summer cooling from cropland albedo increase is strongly amplified during hot summer days, when surface albedo has more impact on the Earth’s radiative balance due to clear-sky conditions. The reduced evaporation associated with the crop residue cover tends to counteract the albedo-induced cooling, but during hot days the albedo effect is the dominating factor. For heatwave summer days the local cooling effect gained from no-till practice is of the order of 2 °C. The identified asymmetric impact of surface albedo change on summer temperature opens new avenues for climate-engineering measures targeting high-impact events rather than mean climate properties.

Concepts: Carbon dioxide, Agriculture, Climate, Temperature, Climate change, Global warming, No-till farming, Tillage

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A two-year experiment was conducted in the field to measure the combined impact of tilling and N fertilization on various agronomic traits related to nitrogen (N) use efficiency and to grain yield in maize cultivated in the presence of a cover crop. Four years after conversion to no-till, a significant increase in N use efficiency N harvest index, N remobilization and N remobilization efficiency was observed both under no and high N fertilization conditions. Moreover, we observed that grain yield and grain N content were higher under no-till conditions only when N fertilizers were applied. Thus, agronomic practices based on continuous no-till appear to be a promising for increasing N use efficiency in maize.

Concepts: Agriculture, Nitrogen, Nitrogen fixation, Maize, Crops, Green manure, No-till farming, Agricultural soil science

2

Tenants and part-owners are farming an increasing number of acres in the United States, while full-owners are farming fewer acres. This shift in ownership is a potential cause for concern because some previous research indicated that tenant and part-owner farmers were less likely to adopt conservation practices than farmers who owned the land they farmed. If that trend persists, ownership changes would signal a national drop in conservation adoption. Here we examine this issue using a survey of agricultural operators in the Clear Creek watershed in Iowa, a state with intensive agricultural production. We compare adoption of conservation practices, and preferences for conservation information sources and communication channels, between farmers who rent some portion of the land they farm (tenants and part-owners) and farmers who own all of the land they farm (full-owners). We find that renters are more likely to practice conservation tillage than full-owners, though they are less likely to rotate crops. In addition, renters report using federal government employees (specifically, Natural Resource Conservation Service and Farm Service Agency) as their primary sources of conservation information, while full-owners most frequently rely on neighbors, friends, and County Extension. These findings are significant for conservation policy because, unlike some past research, they indicate that renters are not resistant to all types of conservation practices, echoing recent studies finding an increase in conservation adoption among non-full-owners. Our results emphasize the importance of government conservation communication and can inform outreach efforts by helping tailor effective, targeted conservation strategies for owners and renters.

Concepts: Agriculture, United States, Natural resource, Farm, Sustainable agriculture, Real estate, No-till farming, Tillage

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Crop residue return is imperative to maintain soil health and productivity but some farmers resist adopting conservation tillage systems with residue return fearing reduced soil temperature following planting and crop yield. Soil temperatures were measured at 10 cm depth for one month following planting from 2004 to 2007 in a field experiment in Northeast China. Tillage treatments included mouldboard plough (MP), no till (NT), and ridge till (RT) with maize (Zea mays L.) and soybean (Glycine max Merr.) crops. Tillage had significant effects on soil temperature in 10 of 15 weekly periods. Weekly average NT soil temperature was 0-1.5 °C lower than MP, but the difference was significant (P < 0.05) only in 2007 when residue was not returned in MP the previous autumn. RT showed no clear advantage over NT in increasing soil temperature. Higher residue coverage caused lower soil temperature; the effect was greater for maize than soybean residue. Residue type had significant effect on soil temperature in 9 of 15 weekly periods with 0-1.9 °C lower soil temperature under maize than soybean residue. Both tillage and residue had small but inconsistent effect on soil temperature following planting in Northeast China representative of a cool to temperate zone.

Concepts: Agriculture, Maize, Crops, No-till farming, Tillage, Harrow, Plough, Advance sowing

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Land use change driven by diet, globalization, and technology advancement have greatly influenced agricultural production and environment in the mollisols region of China, with a marked impact on the depletion of soil organic matter, a signature property of mollisols. Here we report findings on soil organic carbon (SOC) change in three different cropping systems (soybean, soybean/maize, corn) in Northeast China during a 10-year time span. The results indicated that the decline rate of SOC in recent ten years (0.27 g kg-1 yr-1) has slowed down considerably compared to previous decades (1.12 g kg-1 yr-1). Crop system conversion from soybean monocropping to corn monocropping or break system was the critical factor for SOC change, and the background SOC was the second influence factor. When approaching a SOC turning point, conversion from low carbon input crop system (soybeans monocropping) to high carbon input crop system helped slow down the SOC decline (break crop) or even improve SOC (corn monocropping) in mollisols regions. This result implied that imported soybean has brought benefit for Northeast China. But for sustainable goal in China’s mollisols region, straw returning, optimized nitrogen fertilization and no tillage are all necessary whatever in continues maize or rotation system.

Concepts: Agriculture, Soil, Nitrogen, Carbon, Humus, Organic matter, Natural organic matter, No-till farming

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This study was conducted to quantify the potential for CO2 fixation in the above-ground biomass of summer maize (Zea mays L.) under different tillage and residue retention treatments. The treatments were paired and included conventional tillage with straw removed (CT0), conventional tillage with straw retained (CTS), no-till with straw removed (NT0), no-till with straw retention (NTS), subsoiling with straw removed (SS0), and subsoiling with straw retained (SSS). The results indicated that NTS and SSS can enhance translocation of photosynthates to grains during the post-anthesis stage. SSS showed the highest total production (average of 7.8 Mg ha-1), carbon absorption by crop (Cd) (average of 9.2 Mg C ha-1), and total C absorption (Ct) (average of 40.4 Mg C ha-1); and NTS showed the highest contribution of post-anthesis dry matter translocation to grain yield (average of 74%). Higher CO2 emission intensity and CO2 fixation efficiency (CFE) were observed for straw retention treatments. In comparison with CTS, the mean CFE (%) over four years increased by 26.3, 19.0, 16.5, and 9.4 for NT0, SS0, NTS, and SSS, respectively. Thus, SSS and NTS systems offer the best options for removing CO2 from the atmosphere while enhancing crop productivity of summer maize in the North China Plain.

Concepts: Photosynthesis, Carbon dioxide, Agriculture, Arithmetic mean, Cereal, Maize, Rice, No-till farming

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The pre-emergence dinitroaniline herbicides (such as trifluralin and pendimethalin) are vital to Australian no-till farming systems. A Lolium rigidum population collected from the Western Australian grain belt with a 12-year trifluralin use history was characterised for resistance to dinitroaniline, acetyl CoA carboxylase (ACCase)- and acetolactate synthase (ALS)-inhibiting herbicides. Target-site resistance mechanisms were investigated.

Concepts: Agriculture, Acetyl-CoA, Maize, Malonyl-CoA, Acetyl-CoA carboxylase, Herbicide, No-till farming, Tillage

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This 2-year study aimed to verify whether the continuous application of no tillage (NT) for over 20years, in comparison with conventional tillage (CT), affects nitrous oxide (N2O) and ammonia (NH3) emissions from a Vertisol and, if so, whether such an effect varies with crop sequence (continuous wheat, WW and wheat after faba bean, FW). To shed light on the mechanisms involved in determining N-gas emissions, soil bulk density, water filled pore space (WFPS), some carbon © and nitrogen (N) pools, denitrifying enzyme activity (DEA), and nitrous oxide reductase gene abundance (nosZ gene) were also assessed at 0-15 and 15-30cm soil depth. Tillage system had no significant effect on total NH3 emissions. On average, total N2O emissions were higher under NT (2.45kgN2O-Nha(-1)) than CT (1.72kgN2O-Nha(-1)), being the differences between the two tillage systems greater in FW than WW. The higher N2O emissions in NT treatments were ascribed to the increased bulk density, WFPS, and extractable organic C under NT compared to CT, all factors that generally promote the production of N2O. Moreover, compared to CT, NT enhanced the potential DEA (114 vs 16μgNkg(-1)h(-1)) and nosZ gene abundance (116 vs 69 copy number mg(-1) dry soil) in the topsoil. Finally, NT compared to CT led to an average annual increase in C stock of 0.70MgCha(-1)year(-1). Though NT can increase the amount os soil organic matter so storing CO2 into soil, some criticisms related to the increase of N2O emission arise, thereby suggesting the need for defining management strategies to mitigate such a negative effect.

Concepts: Agriculture, Hydrogen, Soil, Nitrogen, Nitric oxide, Humus, Bulk density, No-till farming

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In recent years, yield instability of spring maize becomes increasingly pronounced under the traditional cropping system. In 2014 and 2015, short-term effects of tillage (plow-till, rotary-till and no-till) and residue (removal and incorporation) on soil properties, maize growth and yield were investigated in a brown soil region. Our results indicated that short-term reduced tillage (rotary-till and no-till) and residue incorporation promoted soil properties and maize growth. Compared with plow-till, rotary-till and no-till decreased soil bulk density and compaction below the plough layer (~30 cm). The soil organic carbon (SOC), total nitrogen and C:N of surface soil layers increased under the rotary-till (0-20 cm) and no-till (0-10 cm), which were higher in 0-30 cm soil layers for residue incorporation. For both years, root characteristics of root diameter (RAD) and root surface area density (RSD), biomass indexes of root biomass (RB), shoot biomass (SB) and root-shoot ratio (R:S) were increased under these short-term treatments. Although there were positive relationships between soil water content (SWC), C:N, RAD, RSD, RB, SB, R:S and yield, structural equation modeling showed maize yield was directly controlled by R:S. These findings will have important implications for improving the current cropping system (i.e., plow-till with residue removed) in this area.

Concepts: Density, Water, Soil, Maize, Bulk density, No-till farming, Tillage, Water content