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Incorporating perennial pastures into annual crop systems is an efficient means of improving soil carbon (C) sequestration and reducing the application of nitrogen (N) fertilizer on farmlands. How the soil C and N at different soil depths respond to the length of pasture duration and rainfall conditions is still being determined. In this study, we conducted a meta-analysis of data from 63 published studies to investigate the impacts of the alfalfa pasture on the incorporation of soil organic carbon (SOC), total nitrogen (STN), and available nitrogen (SAN) contents in the 0–300 cm soil profile of the Loess Plateau. An annual crop field was taken as a reference. The results showed that the average SOC content at soil depths of 0–100 and 100–200 cm in the alfalfa pasture increased by 17% and 8% (p < 0.001) compared to the crop field, respectively, while that at 200–300 cm decreased (p > 0.05). The SOC content increased with pasture age; it was the highest when the alfalfa had been planted for 5–9 years and decreased thereafter. The STN content at soil depths of 0–100 and 100–200 cm increased by 19% and 14% (p < 0.001), respectively; the content at depths of 200–300 cm only increased slightly (p > 0.05). It also increased the most when the alfalfa was 5–9 years old. The increments in the SAN content at the 0–100 and 100–200 cm soil depths were higher than those of the STN, with values of 29% and 18%, respectively, while those at depths of 200–300 cm also changed insignificantly (p > 0.05). The SAN content continuously increased with the age of the alfalfa, and the average increment in the 0–300 cm profile was as high as 21% when the alfalfa was ≥10 years old. The SOC and STN content increased the most under moderate rainfall conditions (350–500 mm), while the SAN content maintained the highest increment under high rainfall (500–650 mm) conditions. Therefore, ley farming with the alfalfa pasture contributed substantially to the soil C and N at depths of 200 cm in deep loess. Alfalfa should be removed in its middle ages to increase C sequestration while utilizing soil N efficiently. [ABSTRACT FROM AUTHOR]

Incorporating perennial pastures into annual crop systems is an efficient means of improving soil carbon (C) sequestration and reducing the application of nitrogen (N) fertilizer on farmlands. How the soil C and N at different soil depths respond to the length of pasture duration and rainfall conditions is still being determined. In this study, we conducted a meta-analysis of data from 63 published studies to investigate the impacts of the alfalfa pasture on the incorporation of soil organic carbon (SOC), total nitrogen (STN), and available nitrogen (SAN) contents in the 0–300 cm soil profile of the Loess Plateau. An annual crop field was taken as a reference. The results showed that the average SOC content at soil depths of 0–100 and 100–200 cm in the alfalfa pasture increased by 17% and 8% (p < 0.001) compared to the crop field, respectively, while that at 200–300 cm decreased (p > 0.05). The SOC content increased with pasture age; it was the highest when the alfalfa had been planted for 5–9 years and decreased thereafter. The STN content at soil depths of 0–100 and 100–200 cm increased by 19% and 14% (p < 0.001), respectively; the content at depths of 200–300 cm only increased slightly (p > 0.05). It also increased the most when the alfalfa was 5–9 years old. The increments in the SAN content at the 0–100 and 100–200 cm soil depths were higher than those of the STN, with values of 29% and 18%, respectively, while those at depths of 200–300 cm also changed insignificantly (p > 0.05). The SAN content continuously increased with the age of the alfalfa, and the average increment in the 0–300 cm profile was as high as 21% when the alfalfa was ≥10 years old. The SOC and STN content increased the most under moderate rainfall conditions (350–500 mm), while the SAN content maintained the highest increment under high rainfall (500–650 mm) conditions. Therefore, ley farming with the alfalfa pasture contributed substantially to the soil C and N at depths of 200 cm in deep loess. Alfalfa should be removed in its middle ages to increase C sequestration while utilizing soil N efficiently.

Graphical abstract Highlights • Ryegrass early sowing resulted in earlier forage offering and a decreased soil nitrate content. • Ryegrass early sowing decreased annual N 2 O emissions by 18.5%. • N 2 O emissions were lower for ICL than for the grain production system. Abstract Ryegrass early sowing at the beginning of soybean grain maturation (stage R7) results in an earlier offering of forage for animals in integrated crop-livestock (ICL) systems. In addition, early sowing may decrease N 2 O emissions compared to ryegrass sowing after soybean harvest, although this possibility requires further study. We performed a two-year study to evaluate the effects of ryegrass early sowing in an ICL system under subtropical conditions. The following treatments were tested: (1) ryegrass early sowing into R7 soybean (ICL-I); (2) ryegrass sowing after soybean harvest (ICL-II); and (3) continuous cultivation for grain production with soybean/canola and soybean/wheat successions (CC). We measured the N 2 O fluxes, soil NH 4 + and NO 3 − dynamics, grain yield and forage production. The soybean grain yield was not affected by the ICL and CC systems. Forage was offered earlier in the ICL-I system than in the ICL-II system over the two-year period. Ryegrass forage production was two times higher in the ICL-I system than in the ICL-II system during the first year (5.0 vs 2.3 Mg dry matter ha-1). Ryegrass early sowing efficiently decreased the soil NO 3 − content from soybean stage R7 until the end of the ryegrass cycle. Cumulative N 2 O emissions were positively correlated with nitrate intensity (R2 = 0.95), indicating that practices that decreased the soil NO 3 − accumulation, such as ryegrass early sowing, contributed to decreased N 2 O emissions. The mean cumulative N 2 O emissions for the two-year period was 18.5% lower for ICL-I than for ICL-II (821.3 vs 1007.2 g N-N 2 O ha-1). The cumulative N 2 O emissions were 24 and 21% lower for ICL than for CC for the first and second years, respectively. The present study shows that ryegrass early sowing is an alternative that can decrease annual N 2 O emissions and may contribute to improving the greenhouse gas balance in ICL systems compared to that in grain production systems. [ABSTRACT FROM AUTHOR]

O aumento da demanda pela avaliação da qualidade da estrutura do solo para o adequado crescimento de plantas tem motivado pesquisadores a desenvolverem técnicas visuais de avaliação, a campo, simples e confiáveis para esse fim. No Brasil, um número reduzido de estudos foi realizado empregando métodos visuais de diagnóstico do estado estrutural de solos no campo. Esse trabalho testou a hipótese de que o método de Avaliação Visual da Qualidade da Estrutura do Solo desenvolvido por BALL et al. (2007) para solos de clima temperado pode ser aplicado na identificação de campo da qualidade estrutural de um Latossolo Vermelho Distroférrico sob diferentes sistemas de uso e manejo. Para isso, foram avaliadas amostras indeformadas coletadas de mata preservada (M), sistema de integração lavoura-pecuária (ILP) e sistema plantio direto (SPD). A avaliação da estrutura apoiou-se na aparência, na resistência e nas características das unidades estruturais de blocos de solo e foi definida por cinco escores visuais de classificação de qualidade. O método empregado permitiu distinguir a qualidade do solo de diferentes sistemas de uso e manejo a partir da avaliação da estrutura da camada estudada.The increasing demand for assessing soil structure for crop growth has motivated researchers to develop simple and reliable visual indicators to assess soil structure at the field. There are a few records in Brazil indicating the use of visual techniques for assessing soil physical quality. This paper tested the hypothesis that the Visual Soil Structure Quality Assessment methodology developed by BALL et al. (2007) is reliable for identifying the structural quality of tropical and subtropical soils under different soil management systems. Therefore, the overall objective of this paper was to visually identify the structural quality of an Oxisol under forest, crop-livestock rotation and no-till system. The structure evaluation was based on appearance, strength and characteristics of structural units from soil blocks, and was defined by five visual scores from the classification quality. The method allows distinguishing soil quality of the different soil use and management systems from the evaluation of the layer sampled.

The objective of this work was to assess the effects of integrated crop-livestock systems, associated with two tillage and two fertilization regimes, on the abundance and diversity of the soil macrofauna. Four different management systems were studied: continuous pasture (mixed grass); continuous crop; two crop-livestock rotations (crop/pasture and pasture/crop); and native Cerrado as a control. Macrofauna was sampled using a modified Tropical Soil Biology and Fertility method, and all individuals were counted and identified at the morphospecies level for each plot. A total of 194 morphospecies were found, distributed among 30 groups, and the most representative in decreasing order of density were: Isoptera, Coleoptera larvae, Formicidae, Oligochaeta, Coleoptera adult, Diplopoda, Hemiptera, Diptera larvae, Arachnida, Chilopoda, Lepidoptera, Gasteropoda, Blattodea and Orthoptera. Soil management systems and tillage regimes affected the structure of soil macrofauna, and integrated crop-livestock systems, associated with no-tillage, especially with grass/legume species associations, had more favorable conditions for the development of "soil engineers" compared with continuous pasture or arable crops. Soil macrofauna density and diversity, assessed at morphospecies level, are effective data to measure the impact of land use in Cerrado soils.O objetivo deste trabalho foi avaliar os efeitos de sistemas de integração lavoura-pecuária, associados a dois tipos de preparo e de fertilização do solo, sobre a abundância e a diversidade da macrofauna edáfica. Quatro sistemas de manejo foram estudados: pastagem contínua de gramíneas; lavoura contínua de culturas anuais; dois sistemas integrados lavoura-pecuária (lavoura/pastagem e pastagem/lavoura); e Cerrado nativo (controle). A macrofauna foi avaliada pelo método "Tropical Soil Biology and Fertility" modificado e todos os indivíduos coletados nas parcelas foram contados e identificados ao nível de morfoespécies. O total de 194 morfoespécies foi encontrado, distribuído entre 30 grandes grupos, dos quais os mais representativos em ordem decrescente de densidade foram: Isoptera, larvas de Coleoptera, Formicidae, Oligochaeta, adultos de Coleoptera, Diplopoda, Hemiptera, larvas de Diptera, Arachnida, Chilopoda, Lepidoptera, Gasteropoda, Blattodea e Orthoptera. Os sistemas de uso e de preparo do solo afetaram a estrutura das comunidades da macrofauna edáfica. Os sistemas de integração lavoura-pecuária, associados ao plantio direto na fase lavoura, especialmente com a rotação gramíneas/leguminosas, tiveram as melhores condições para o desenvolvimento das espécies de "engenheiros do solo" em comparação às pastagens e às culturas contínuas. A densidade e a diversidade da macrofauna, avaliadas em nível de morfo-espécies, são dados eficientes para medir o impacto de diferentes sistemas de uso da terra, em solos do Cerrado.

O objetivo deste trabalho foi avaliar o impacto de sistemas de integração lavoura-pecuária sobre atributos físico-hídricos do solo e avaliar o potencial uso desses atributos como indicadores da qualidade física de um Latossolo. As amostras de solo foram coletadas nas camadas 0-5, 10-15, 20-25 e 40-45 cm. Todos os sistemas de uso e manejo do solo alteraram significativamente a densidade, umidade volumétrica, resistência à penetração, porosidade total, macroporosidade, microporosidade efetiva e água prontamente disponível do solo. Foram observados incrementos na resistência à penetração e na densidade do solo em todos os sistemas em comparação ao cerrado nativo. A compactação resultante do pisoteio animal durante quatro anos da fase pastagem, nos sistemas de integração lavoura-pecuária, não atingiu valores críticos, que pudessem limitar cultivos anuais subseqüentes. A porosidade total e a macroporosidade foram maiores no cerrado e nos sistemas em plantio direto em relação aos em preparo convencional. Os atributos avaliados são indicadores confiáveis da qualidade físico-hídrica do solo.The objective of this work was to analyze the effect of integrated crop-livestock systems on soil hydraulic properties, and test the potential use of these properties as physical quality indicators of a Cerrado Oxisol. The field study was conducted at Embrapa Cerrados, Planaltina, DF, Brazil, considering soil layers of: 0-5, 10-15, 20-25 and 40-45 cm. Crop-livestock systems caused significant changes in soil bulk density, volumetric soil-water content, soil penetration resistance, total porosity, macroporosity, effective microporosity, unsaturated pores and available water. An increase was observed in both soil resistance and bulk density for all systems in comparison to the cerrado. However, higher soil resistance did not appear as a limiting factor for annual crops growth in a rotation sequence. Total porosity and macroporosity were higher in the cerrado, and in the systems with no-tillage in relation to conventional tillage. Soil penetration resistance, macroporosity, bulk density and available soil-water properties are reliable indicators of the soil physical quality.

Integrated crop-livestock systems (ICL) have played an important role in human civilisation and have dominated the broadacre agricultural production system in the wheat-sheep zone of Australia. Over the past couple of decades, an increase in grain prices and decline in wool prices have led to the expansion of cropping into the high rainfall zone (HRZ) in southern Australia. While there has been a great deal of research into integrated crop-livestock systems for the medium to low rainfall environments in the wheat-sheep zone, there is much less information and many challenges confronting farmers to effectively integrate crops into the grazing systems in the high rainfall zone due to climatic and environmental differences and the complexity of the systems in Australia. This paper reviews the benefits of integrated crop-livestock systems and the challenges in implementing and managing these systems based on current Australian and international knowledge. The concept, types and terminology of integrated crop-livestock systems are discussed to provide greater clarity. Plant species, particularly annual and perennial legumes, are reviewed to find species with potential for use in integrated crop-livestock systems. Major gaps and opportunities for further research and development are identified, and recommendations proposed for developing effective integrated crop-livestock systems for the HRZ. These include: 1) Targeted R&D on ICL systems in the HRZ of southern Australia assisted with information from and outside Australia; 2) Biophysical and bio-economic modelling using current knowledge from the HRZ and other environments to guide future research; 3) Studies on N fixation, transfer and losses to develop strategies to balance N cycling and reduce N losses; 4) Development of compatible species/cultivars for ICL systems in the HRZ; 5) Management of waterlogging through ICL in the HRZ; 6) Effective stubble management to minimise the negative impact on crops and pastures; 7) Integrated research on grain yield reduction in crop-pasture intercropping, a potentially major type of ICL systems in the HRZ; and 8) Effective control of weeds, pests and diseases in ICL systems for the HRZ. [ABSTRACT FROM AUTHOR]

Highlights: [•] We evaluated areas under land use change in the Brazilian Cerrado. [•] Conversion of NV to pasture reduces C stock and increases N2O and CH4 emission. [•] Conversion of NV to agriculture reduces C stock and increases N2O and CH4 emission. [•] Crop-pasture rotation systems reduce net GHG emission from the soil. [Copyright &y& Elsevier]

Abstract: Soil organic carbon (SOC) is one of the principal indicators of soil quality. Its size fractions have been proposed as high sensitivity indicators in order to detect changes generated by different soil use and management intensities. The objective was to compare the impact of different soil management practices after 10 years on SOC distribution and its size fractions. Treatments consisted in two rotation systems (rotations of continuous annual crops and rotations of 3 years of crops and 3 years of pastures), performed with conventional tillage (CT) and no-till (NT). In 2000, NT treatments were additionally split into C3 or C4 summer crops. In 2003, soil was sampled at 0–3, 3–6, 6–12, 12–18, 18–40, 40–60 and 60–80cm depths and SOC was determined. At the first four depths, SOC associated with particulate organic matter (POM-C) and with the soil mineral fraction (MAOM-C) were determined. Changes in carbon indicators (SOC and its size fractions) occurred mainly in the first 3cm of soil, and with the exception of POM-C, were diluted when considering the 0–18cm depth. Inclusion of pastures in the rotation was a better alternative to continuous cropping in CT systems, since it had better C indicator values. However, NT improved indicator values compared with LC, especially when C4 species were included in the rotation; no differences were found between continuous cropping or crop-pasture rotations. These results allowed discriminate different combinations of crops and tillage systems that contribute to maintain or increase SOC, suggesting a sustainable management of the soil resource. [Copyright &y& Elsevier]

Abstract: Integrated crop–livestock management systems (ICLS) have been increasingly recommended in Brazilian agroecosystems. However, knowledge of their effect on soil organic carbon (SOC) and total nitrogen (TN) concentrations and stocks is still limited. The study was undertaken to evaluate the effects of ICLS under two tillage and fertilization regimes on SOC and TN concentrations and stocks in the 0–30cm soil layer, in comparison with continuous crops or pasture. The following soil management systems were studied: continuous pasture; continuous crop; 4 years’ crop followed by 4 years’ pasture and vice-versa. The adjacent native Cerrado area was used as a control. Under the rotation and continuous crop systems there were two levels of soil tillage (conventional and no-tillage) and fertility (maintenance and corrective fertility). The stock calculations were done using the equivalent soil mass approach. The land use systems had a significant effect on the concentrations of SOC and TN in the soil, but no effect was observed for the soil tillage and fertilizer regimes. For these two latter, some significant discrepancies appeared in the distribution of SOC and TN concentrations in the 0–30cm layer. Carbon storage was 60.87Mgha−1 under Cerrado, and ranged from 52.21Mgha−1 under the ICLS rotation to 59.89Mgha−1 with continuous cropping. The decrease in SOC stocks was approximately 8.5 and 7.5Mgha−1, or 14 and 12%, for continuous pasture and ICLS respectively. No-tillage for 10 years after the conversion of conventional tillage to no-tillage under the continuous crop system, and 13 years of conventional tillage in continuous cropping did not result in significant changes in SOC stocks. The SOC and TN stocks in surface layers, using the equivalent soil mass approach rather than the equivalent depth, stress the differences induced by the calculation method. As soil compaction is the principal feature of variability of stocks determinations, the thickness should be avoid in these types of studies. [Copyright &y& Elsevier]