The Science

man in a face mask standing in front of a farm field

The tragedy of the COVID-19 pandemic has once again indicated the need for protecting, regenerating and sustaining our depleted and fragile soil. This article points out lessons of this crisis that can be used to make a stronger case for paving the way forward to more effectively combat climate change and better ensure food security.

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Recycling old almond tree biomass in situ prior to replanting an orchard is known as whole orchard recycling (WOR). It has potential as a carbon (C) negative practice to build soil C storage, soil health, and orchard productivity. Researchers in this study tested the potential of this practice for long term C sequestration and found it effective. It also led to higher yields and substantial improvement in soil functioning, including nutrient content, aggregation, porosity, and water retention.

Even though we know that the soil microbiome is highly diverse and comprises up to one quarter of Earth’s diversity, it is still not clear how such a complex microbiome influences ecosystem functioning. In this study the authors of this report manipulated the soil microbiome in experimental grassland ecosystems.The findings indicate the importance of microbial interactions within and among fungal and bacterial communities for enhancing ecosystem performance. They also demonstrate that extinction of complex ecological associations below ground can impair ecosystem functioning. See the full findings.

This study found that rangelands managed with more regenerative practices and lack of ivermectin applications had greater species richness, diversity, predator species abundance, and dung beetle abundance than more conventionally managed rangelands. The work shows that herd management that aims to mimic intensive grazing of large migrating herds of ruminants can foster dung arthropod community structure, a key trait correlated with nutrient cycling, pest suppression, and productivity of cattle-grazed rangelands. Read the paper.

The American Farmland trust used a USDA Conservation Innovation Grant to quantify the economic and environmental benefits of soil health practices (no-till, strip-till, cover crops, nutrient management, conservation cover, compost application, and mulching). They also used the USDA’s Nutrient Tracking Tool and USDA’s COMET-Farm Tool to quantify the water quality and climate benefits of these practices. The results, including four 2-page case studies, are available on their site.

New research by Alexandra Kravchenko, Michigan State University professor in the Department of Plant, Soil and Microbial Sciences, and several of her colleagues provides new insight into how carbon is stored in soils that could support efforts to improve the climate resilience of cropping systems and also reduce their carbon footprints. Read more . . . Read the original paper here.

Abstract: "Modern agriculture is associated with numerous environmental predicaments, such as land degradation, water pollution, and greenhouse gas emission. Socio-economically, it is characterized by a treadmill of technological change, increased mechanization, and economic consolidation, while depressing economic returns to farmers. A root cause is the dominance of annual plants cultivated in monocultures. Annual crops require the yearly clearing of vegetation resulting in soil erosion and other forms of ecosystem degradation. Monocultures are susceptible to agricultural pests and weeds. By contrast, perennial polycultures informed by natural ecosystems, promise more sustainable agroecosystems with the potential to also revitalize the economic foundation of farming and hence rural societies." Read the paper.

field with cover crops This paper summarizes how agricultural systems developed into what they are today and identifies ways in which these systems will need to be improved to meet future food security challenges. The core principles and concepts of conservation agriculture (CA) systems provide an important unifying framework. The paper provides evidence for why these systems, when flexibly applied and in ways that mimic natural ecosystems, provide the best approach for moving forward. Read the paper in full.(opens in new window)

Bioinoculants are an increasing trend in agricultural practices. This review explores recent advances in our understanding of how arbuscular mycorrhizal fungi, ectomycorrhizal fungi, and phosphate-solubilizing bacteria help solubilize inorganic phosphate from insoluble forms and allocate it directly to crop plants. Read the full report.

Abstract: Biodiversity of insects is threatened worldwide. Here, we present a comprehensive review of 73 historical reports of insect declines from across the globe, and systematically assess the underlying drivers. Our work reveals dramatic rates of decline that may lead to the extinction of 40% of the world's insect species over the next few decades. Read more . . .

Abstract: "Global crop yield gains have not been associated with increases in the many macro- and micro-nutrients needed for a balanced human diet. There is thus growing interest in improving agricultural practices to increase nutrient availability to people. Because nutrients in crops come from soil, soil management—such as building soil organic matter—could be a tool in managing agriculture to produce more nutritious food. To understand the relationship between soil organic matter and nutritional quality, we measured soil organic matter fractions, crop yield, and wheat nutrient composition on smallholder farms along a land-use and land-cover gradient in Ethiopia. We found that wheat yields and protein content were related to organic matter nitrogen, and zinc content was related to organic matter carbon." Read the paper in full.

Sun shining over a meadow with trees Abstract: Limiting climate warming to <2°C requires increased mitigation efforts, including land stewardship, whose potential in the United States is poorly understood. We quantified the potential of natural climate solutions (NCS)—21 conservation, restoration, and improved land management interventions on natural and agricultural lands—to increase carbon storage and avoid greenhouse gas emissions in the United States. Read more . . . (opens in new window)

Jumping Spider Abstract: Most spiders are generalist predators and important biological control agents of various insect pests of agri-cultural crops. A study was conducted to determine the impact of cultural practices on the abundance and diversity of soil surface-dwelling spiders (Araneae). Two experiments were conducted at the Chinhoyi University of Technology experimental farm, Zimbabwe, over the 2013/2014 and 2014/2015 cropping seasons. Read more . . .(opens in new window)

Map of California showing the Agricultural Vulnerability index.

California is a global leader in the agricultural sector and produces more than 400 types of commodities. The state produces over a third of the country’s vegetables and two-thirds of its fruits and nuts. Despite being highly productive, current and future climate change poses many challenges to the agricultural sector. This paper provides a summary of the current state of knowledge on historical and future trends in climate and their impacts on . . . Read more . . .

This paper evaluates the relative effects of regenerative and conventional corn production systems on pest management services, soil conservation, and farmer profitability and productivity. It shows that regenerative farming systems provided greater ecosystem services and profitability for farmers than an input-intensive model of corn production. Regenerative fields had ten times fewer pests. And even though regenerative fields had 29% lower yields, profits were 78% higher than traditional corn production systems. Read the full article.

Abstract: Plant diversity has been shown to determine the composition and functioning of soil biota. Although root-derived organic inputs are discussed as the main drivers of soil communities, experimental evidence is scarce. While there is some evidence that higher root biomass at high plant diversity increases substrate availability for soil biota, several studies have speculated that . . . Read more . . .

Despite several lines of observational evidence, there has been a lack of consensus on whether higher fungal:bacterial (F:B) ratios directly cause higher soil carbon (C) storage. This team employed RNA sequencing, protein profiling and isotope tracer techniques to evaluate whether differing F:B ratios are associated with differences in C storage. In the experiments they performed the increased abundance of fungi in both soils and the altered C cycling patterns in the F:B dominated soils highlight the significant role of fungi in litter decomposition and indicate that F:B ratios are linked to higher C storage potential. Read the full report.

Because of the methane produced by rumen fermentation, ruminants are a source of greenhouse gas and are perceived as a problem. However, research shows that ruminants consuming only grazed forage cover plants under appropriate management result in more C sequestration than emissions. This research editorial concludes that incorporating forages and ruminants into regeneratively managed agroecosystems should be advanced as a policy. It can elevate soil organic C, improve soil ecological function by minimizing the damage of tillage and inorganic fertilizers and biocides, and enhance biodiversity and wildlife habitat. Read the entire editorial. (PDF)

Abstract: Loss of soil organic carbon (SOC) from agricultural land is identified as one of the major threats to soils, as it influences both fertility and the production of ecosystem services from agriculture. Losses of SOC across regions are often determined by monitoring in different land use systems. Results from agricultural field experiments can reveal . . . Read more . . .

Abstract: The goal of microbiome engineering is to manipulate the microbiome toward a certain type of community that will optimize plant functions of interest. For instance, in crop production the goal is to reduce disease susceptibility, increase nutrient availability increase abiotic stress tolerance and increase crop yields. Various approaches can be devised to engineer the plant–microbiome, but one particularly promising approach is to take advantage of naturally evolved plant–microbiome communication channels. Read more . . .

Plant diversity strongly influences ecosystem functions and services, such as soil carbon storage. However, the mechanisms underlying the positive plant diversity effects on soil carbon storage are poorly understood. We explored this relationship using long-term data from a grassland biodiversity experiment (The Jena Experiment) and radiocarbon (14C) modeling. Read more . . .

An 11-year grassland biodiversity experiment investigated whether plant diversity affects soil C and N storage in the absence of legumes. They found that soil C and N stocks increased by 18% and 16% in eight-species mixtures compared to the average of monocultures of the same species, respectively. Enhanced soil C and N stocks also showed a positive feedback to plant productivity via enhanced N mineralization, which could further accelerate soil C and N storage in the long term. Read more . . .

Hands holding soil with an earthworm in it Increased long term (20-50 year) sequestration of carbon in soils, plants and plant products will benefit the environment and agriculture. Crop, grazing, and forestlands can be managed for both economic productivity and carbon sequestration. In many settings this dual management approach can be achieved by applying currently recognized best management practices such as conservation tillage, efficient nutrient management, erosion control, use of cover crops and restoration of degraded soils. Read more . . . (PDF)