Intensive crop production on grassland-derived Mollisols has liberated massive amounts of carbon (C) to the atmosphere. Whether minimizing soil disturbance, diversifying crop rotations, or re-establishing perennial grasslands and integrating livestock can slow or reverse this trend remains highly uncertain. We investigated how these management practices affected soil organic carbon (SOC) accrual and distribution between particulate (POM) and mineral-associated (MAOM) organic matter in a 29-y-old field experiment in the North Central United States and assessed how soil microbial traits were related to these changes. Compared to conventional continuous maize monocropping with annual tillage, systems with reduced tillage, diversified crop rotations with cover crops and legumes, or manure addition did not increase total SOC storage or MAOM-C, whereas perennial pastures managed with rotational grazing accumulated more SOC and MAOM-C (18 to 29% higher) than all annual cropping systems after 29 y of management. These results align with a meta-analysis of data from published studies comparing the efficacy of soil health management practices in annual cropping systems on Mollisols worldwide. Incorporating legumes and manure into annual cropping systems enhanced POM-C, microbial biomass, and microbial C-use efficiency but did not significantly increase microbial necromass accumulation, MAOM-C, or total SOC storage. Diverse, rotationally grazed pasture management has the potential to increase persistent soil C on Mollisols, highlighting the key role of well-managed grasslands in climate-smart agriculture.

-Integrated crop-livestock systems (ICLS) are designed to exploit synergisms and emergent properties resulting from interactions between different soil-plant-animal-atmosphere compartments that integrate themselves at different spatial-temporal scales. In this review, a panorama of the evolution of studies based on ICLS is presented. Specific keywords were used as search terms to construct a database of 450 articles from 93 national and international journals published up to and including 2013. These articles were classified according to the region of origin within Brazil (subtropical or tropical) and categorized regarding the studied components: soil, plant, animal and 'others'. Within these components, groups of variables that could characterize the different thematic lines were listed. The number of publications worldwide has been increasing, and Brazil is one of the main suppliers of scientific work within this area. Although the number of scientific studies seeking better understanding of ICLS may have increased in Brazil, further studies with a systematic view and with larger temporal and spatial scales are still required to help identify interactions between diverse biotic and abiotic factors that define new properties that emerge from these systems.Key words: Conservation agriculture. Sustainability. Scientific production. Agricultural technology. Systematic approach.RESUMO -Os sistemas integrados de produção agrícola e pecuária são caracterizados como sistemas planejados para explorar sinergismos e propriedades emergentes, resultado de interações entre os diferentes compartimentos solo-plantaanimal-atmosfera, que se integram em diferentes escalas espaço-temporais. Nesta revisão é apresentado um panorama da evolução das pesquisas embasadas em uma produção integrada entre os diferentes compartimentos. Considerou-se o período até 2013 e palavras-chave como fator de busca, sendo construída uma base de dados, partindo de um universo de 450 artigos em 93 periódicos nacionais e internacionais. Estes artigos foram classificados de acordo com a região de origem do Brasil: subtropical ou tropical; e categorizados quanto aos componentes: solo, planta, animal e outros. Dentro desses componentes foram elencados grupos de variáveis que caracterizassem diferentes linhas temáticas. As publicações no mundo têm aumentado e o Brasil está entre os principais provedores de trabalhos científicos nessa área. Embora seja crescente o número de trabalhos científicos no Brasil, que buscam melhor compreensão dos sistemas integrados de produção agrícola e pecuária, as pesquisas com visão sistêmica e de maior escala temporal e espacial ainda necessitam de mais estudos, para que possam detectar interações entre os diversos fatores bióticos e abióticos e novas propriedades que emergem destes sistemas.Palavras-chave: Agricultura conservacionista. Sustentabilidade. Produção científica. Tecnologia agropecuária. Enfoque sistêmico.

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Production systems that feature temporal and spatial integration of crop and livestock enterprises, also known as integrated crop-livestock systems (ICLS), have the potential to intensify production on cultivated lands and foster resilience to the effects of climate change without proportional increases in environmental impacts. Yet, crop production outcomes following livestock grazing across environments and management scenarios remain uncertain and a potential barrier to adoption, as producers worry about the effects of livestock activity on the agronomic quality of their land. To determine likely production outcomes across ICLS and to identify the most important moderating variables governing those outcomes, we performed a meta-analysis of 66 studies comparing crop yields in ICLS to yields in unintegrated controls across 3 continents, 12 crops, and 4 livestock species. We found that annual cash crops in ICLS averaged similar yields (-7% to +2%) to crops in comparable unintegrated systems. The exception was dual-purpose crops (crops managed simultaneously for grazing and grain production), which yielded 20% less on average than single-purpose crops in the studies examined. When dual-purpose cropping systems were excluded from the analysis, crops in ICLS yielded more than in unintegrated systems in loamy soils and achieved equal yields in most other settings, suggesting that areas of intermediate soil texture may represent a "sweet-spot" for ICLS implementation. This meta-analysis represents the first quantitative synthesis of the crop production outcomes of ICLS and demonstrates the need for further investigation into the conditions and management scenarios under which ICLS can be successfully implemented.

Abstract. Soil organic and inorganic phosphorus (P) compounds can be influenced by distinctive environmental properties. This study aims to analyze soil P composition in natural ecosystems, relating organic (inositol hexakisphosphate, DNA and phosphonates) and inorganic (orthophosphate, polyphosphate and pyrophosphate) compounds with major temporal (weathering), edaphic and climatic characteristics. A dataset including 88 sites was assembled from published papers that determined soil P composition using one-dimensional liquid state 31P nuclear magnetic resonance spectroscopy of NaOH-EDTA extracts of soils. Bivariate and multivariate regression models were used to better understand the environmental properties influencing soil P. In bivariate relationships, trends for soil P compounds were similar for mineral and organic layers but with different slopes. Independent and combined effects of weathering, edaphic and climatic properties of ecosystems explained up to 78 % (inositol hexakisphosphates) and 89 % (orthophosphate) of variations in organic and inorganic P compounds across the ecosystems, likely deriving from parent material differences. Soil properties, particularly pH, total carbon, and carbon-to-phosphorus ratios, over climate and weathering mainly explained the P variation. We conclude that edaphic and climatic drivers regulate key ecological processes that determine the soil P composition in natural ecosystems. These processes are related to the source of P inputs, primarily determined by the parent material and soil forming factors, plant and microbe P cycling, the bio-physico-chemical properties governing soil phosphatase activity, soil solid surface specific reactivity, and P losses through leaching, and finally the P persistence induced by the increasing complexity of organic and inorganic P compounds as the pedogenesis evolves. Soil organic and inorganic P compounds respond differently to combinations of environmental drivers, which likely indicates that each P compound has specific factors governing its presence in natural ecosystems.

There is an increased interest in using diffuse reflectance infrared Fourier transform spectroscopy in the mid‐infrared region (mid‐DRIFTS) for high‐throughput prediction of soil properties, but basic methodological factors toward this end have yet to be thoroughly vetted. This study aimed to determine how the combined effects of soil grinding (sieved to <2.0 mm and finely ground to <0.5 mm) and sample replication (single or multiple soil subsamples, using one‐to‐four replicates) affect the spectral quality and predictive performance (accuracy) of automated plate‐based mid‐DRIFTS for soil analysis. We evaluated chemometric prediction performance of soil physical, chemical, and biological variables (clay, sand, pH, total organic C, and permanganate‐oxidizable C [POXC]) in 397 soils from the U.S. Midwest. Sieved soils (<2.0 mm) increased the overall spectral variability compared to finely ground soils (<0.5 mm) and led to a distinct wavenumber importance allocation in support vector machine models. These spectral changes degraded prediction performance of <2.0 mm samples when compared to <0.5 mm samples. The number of spectral replicates had a smaller effect on spectral properties, but impacted prediction accuracies of soil properties. In general, prediction outcomes improved with four spectral replicates either within a single soil subsample or across different soil subsamples. Our data collectively suggest that soil particle‐size reduction to <0.5 mm and collecting multiple spectra improve mid‐DRIFTS predictions. Recommendations to optimize high‐throughput mid‐DRIFTS should consider the tradeoffs between prediction accuracy and the effort needed to prepare soil samples and acquire spectra.