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Abstract No-till management is often recognized for its environmental and economic benefits, but its potential to reduce climate warming is still uncertain. Beyond ongoing debate over its effects on soil carbon storage, no-till also leaves plant residue on the surface, which can reflect more sunlight. This increase in surface reflectivity, called albedo, may help mitigate climate change by reducing the energy absorbed by the land. Here, we assessed this climate benefit of no-till across the U.S. Corn Belt using conservation survey records, county-level tillage data, and satellite observations. We found that no-till increased land surface brightness during the dormant season, reducing absorbed solar energy by an estimated 50 grams of CO₂equivalent per square meter per year. Regionally, this could add up to 24 teragrams of CO₂equivalent per year in potential climate benefits. Areas with low adoption, especially those with dark, carbon-rich soils, offer the greatest opportunity for further mitigation. 

Abstract Worldwide, voluntary agri-environmental programs encourage farmers to adopt environmentally friendly practices. However, the impact of program design on farmers’ participation and long-term practice persistence is unclear. Toward improving program effectiveness, this study illustrates the value of a tailored practice-specific approach to agri-environmental program design. We present a case study of programs promoting cover crops, a conservation practice that can improve soil health and reduce nutrient pollution, drawing from five focus groups with farmers (n = 20) and program administrators (n = 14) in the U.S. Midwest (Iowa, Illinois, and Indiana). Participants perceived cover crop programs to best support farmers is characterized by flexibility and minimal transaction costs. Participants suggested a more data-driven approach to program design particularly for understanding the farm-level economic implications of cover crop use. Integrating financial planning and participatory research components alongside traditional financial incentives and technical assistance were proposed as valuable strategies to enhance program design and broaden the appeal of conservation practices like cover crops. 

Abstract Widespread shifts in land cover and land management (LCLM) are being incentivized as tools to mitigate climate change, creating an urgent need for prognostic assessments of how LCLM impacts surface energy balance and temperature. Historically, observational studies have tended to focus on how LCLM impacts surface temperature (T_surf), usually at annual timescales. However, understanding the potential for LCLM change to confer climate adaptation benefits, or to produce unintended adverse consequences, requires careful consideration of impacts on bothT_surfand the near-surface air temperature (T_a,local) when they are most consequential for ecosystem and societal well-being (e.g. on hot summer days). Here, long-term data from 130 AmeriFlux towers distributed between 19–71 °N are used to systematically explore LCLM impacts on bothT_surfandT_a,local, with an explicit focus on midday summer periods when adaptive cooling is arguably most needed. We observe profound impacts of LCLM onT_surfat midday, frequently amounting to differences of 10 K or more from one site to the next. LCLM impacts onT_a,localare smaller but still significant, driving variation of 5–10 K across sites. The magnitude of LCLM impacts on bothT_surfandT_a,localis not well explained by plant functional type, climate regime, or albedo; however, we show that LCLM shifts that enhance ET or increase canopy height are likely to confer a local mid-day cooling benefit for bothT_surfandT_a,localmost of the time. At night, LCLM impacts on temperature are much smaller, such that averaging across the diurnal cycle will underestimate the potential for land cover to mediate microclimate when the consequences for plant and human well-being are most stark. Finally, during especially hot periods, land cover impacts onT_a,localandT_surfare less coordinated, and ecosystems that tend to cool the air during normal conditions may have a diminished capacity to do so when it is very hot. We end with a set of practical recommendations for future work evaluating the biophysical impacts and adaptation potential of LCLM shifts. 

Nitrogen (N) fertilizer enhances crop production, but field runoff impacts water quality in adjacent freshwaters. Planting winter cover crops reduces nitrate-N losses during the fallow period, but less is known about impacts on ammonium-N. From 2016–2023, we sampled biweekly from the Shatto Ditch and Kirkpatrick Ditch Watersheds in Indiana (USA) to compare the impact of cover crops on dissolved inorganic nitrogen at the field-, edge-of-field, and watershed-scales. We measured soil ammonium-N and nitrate-N, biomass, and organic matter in fall and spring. Cover crops reduced soil ammonium-N at Shatto and soil nitrate-N in both watersheds. Tile losses and watershed yields of ammonium-N occurred on scales orders of magnitude lower than nitrate-N. Tile ammonium-N losses from cover cropped fields ranged from 97 % lower to 31 % higher at Shatto, and 45 % lower to 75 % higher at Kirkpatrick compared to those without. Cover crops reduced field-scale nitrate-N losses at Shatto by 58–87 %, but losses at Kirkpatrick ranged 99 % lower to 15 % higher. Tile flow explained interannual variation in nitrate-N losses, while field-scale ammonium-N losses were driven by soil and microbial interactions and mobilization during storms. Watershed-scale ammonium-N and nitrate-N yields correlated with runoff (Kendall τ=0.45 and 0.39, respectively). While nitrate-N yields mirrored runoff, ammonium-N yields exhibited a step-functional increase, pointing to the importance of storms as a driver of loss. As Midwest crop production adapts to fluctuating environmental conditions, we demonstrate how applying cover crops over a multi-year period can mitigate ammonium-N losses 

Nutrient runoff from agricultural regions of the midwestern U.S. corn belt has degraded water quality in many inland and coastal water bodies such as the Great Lakes and Gulf of Mexico. Under current climate, observational studies have shown that winter cover crops can reduce dissolved nitrogen and phosphorus losses from row-cropped agricultural watersheds, but performance of cover crops in response to climate variability and climate change has not been systematically evaluated. Using the Soil & Water Assessment Tool (SWAT) model, calibrated using multiple years of field-based data, we simulated historical and projected future nutrient loss from two representative agricultural watersheds in northern Indiana, USA. For 100% cover crop coverage, historical simulations showed a 31–33% reduction in nitrate (NO3−) loss and a 15–23% reduction in Soluble Reactive Phosphorus (SRP) loss in comparison with a no-cover-crop baseline. Under climate change scenarios, without cover crops, projected warmer and wetter conditions strongly increased nutrient loss, especially in the fallow period from Oct to Apr when changes in infiltration and runoff are largest. In the absence of cover crops, annual nutrient losses for the RCP8.5 2080s scenario were 26–38% higher for NO3−, and 9–46% higher for SRP. However, the effectiveness of cover crops also increased under climate change. For an ensemble of 60 climate change scenarios based on CMIP5 RCP4.5 and RCP8.5 scenarios, 19 out of 24 ensemble-mean simulations of future nutrient loss with 100% cover crops were less than or equal to historical simulations with 100% cover crops, despite systematic increases in nutrient loss due to climate alone. These results demonstrate that planting winter cover crops over row-cropped land areas constitutes a robust climate change adaptation strategy for reducing nutrient losses from agricultural lands, enhancing resilience to a projected warmer and wetter winter climate in the midwestern U.S.