Population Dynamics of Fall Armyworm (Lepidoptera: Noctuidae) in Maize Fields in Uganda.

Spodoptera frugiperda (Lepidoptera: Noctuidae), commonly known as fall armyworm, was first detected in Uganda in 2016 and has spread to all the maize-growing districts. Different methods have been deployed to control this pest. However, there is a limited understanding of the role of the environment and farmers' practices on the abundance of and damage by S. frugiperda in Uganda. This study, therefore, assessed the abundance of S. frugiperda and leaf damage levels in three different districts and explored the association between agronomic practices, crop phenology, and weather parameters on S. frugiperda damage and abundance in smallholder farmers' maize fields using a longitudinal monitoring survey in 69 farmers' fields of Kole, Kiryandongo, and Nakaseke for three seasons. The numbers of egg masses and adults were generally low. The highest numbers of adults were trapped in Kiryandongo, followed by Nakaseke, and the lowest numbers were trapped in Kole. Leaf damage and incidence of damaged plants differed significantly between districts and seasons. Leaf damage and abundance of larvae varied significantly in the districts and at different growth stages. Conservation tillage, reduced weeding frequency, increased rainfall and high maximum temperatures were associated with reduced S. frugiperda damage. No significant relationship was observed between pesticide or cropping systems with S. frugiperda leaf damage. However, the influence of fertilizer use on leaf damage was contradictory across seasons and districts. Timely and vigilant scouting, proper timing of control measures, and minimum tillage practices should be included in an IPM strategy for S. frugiperda.

Impact of historical soil management on the interaction of plant-growth-promoting bacteria with maize (Zea mays L.).

Edaphic factors can modulate the effects of microbial inoculants on crop yield promotion. Given the potential complexity of microbial inoculant responses to diverse soil management practices, we hypothesize that sustainable management of soil and water irrigation may improve soil quality and enhance the effects of plant growth-promoting bacteria (PGPB). Consequently, the primary objective was to assess the effectiveness of microbial inoculants formulated with Herbaspirillum seropedicae (Hs) and Azospirillum brasilense (Ab) on maize growth in soils impacted by different historical conservation management systems. We evaluated two soil management systems, two irrigation conditions, and four treatments: T0 - without bioinoculant and 100% doses of NPK fertilization; T1 - Hs + humic substances and 40% of NPK fertilization; T2 - Ab and 40% of NPK fertilization; T3 - co-inoculation (Hs + Ab) and 40% of NPK fertilization. Using a reduced fertilization dose (40% NPK) associated with microbial inoculants proved efficient in increasing maize shoot dry mass : on average, there was a 16% reduction compared to the treatment with 100% fertilization. In co-inoculation (Hs + Ab), the microbial inoculants showed a mutualistic effect on plant response, higher than isolate ones, especially increasing the nitrogen content in no-tillage systems irrigated by swine wastewater. Under lower nutrient availability and higher biological soil quality, the microbial bioinputs positively influenced root development, instantaneous water use efficiency, stomatal conductance, and nitrogen contents.

"Effects of soil management, rotation and sequence of crops on soil nitrous oxide emissions in the Cerrado: A multi-factor assessment".

The emission of nitrous oxide (N2O), one of the main greenhouse gases, which contributes significantly to global warming, is a major challenge in modern agriculture. The effects of land use systems on N2O emissions are the result of multiple variables, whose interactions need to be better understood. In this sense, this study analyzed the possible effects of different soil managements, crop rotations and sequences, as well as edaphoclimatic factors causing N2O emissions from soils in the Cerrado biome (scrubland). The following four land-use systems were evaluated: 1) No-tillage cultivation with biennial crop rotations and sequences: legume-grass and alternating grass-legume crops in the second season - NT-SS/MP; 2) No-tillage with biennial rotations and sequences: grass-legume and alternating second crop of legume-grass - NT-MP/SS; 3) Conventional planting with disc harrow and biennial legume-grass rotation-CT-S/M; and 4) Native Cerrado (CE), no agricultural land use. The legume and grass species, planted in the two no-tillage treatments were soybean, followed by sorghum BRS3.32 (Sorghum bicolor (L.) Moench) (SS), and maize, followed by pigeon pea (Cajanus cajan) (MP). Nitrous oxide emissions were evaluated for 25 months (October 2013 to October 2015), and the results were grouped in annual, total, growing and non-growing seasons, as well as yield-scaled N2O emissions. The mean N2O fluxes were 24.14, 15.71, 32.49 and 1.87 µg m-2 h-1 in the NT-SS/MP, NT-MP/SS, CT-S/M and Cerrado areas respectively. Cumulative N2O fluxes over the total evaluation period from the systems NT-SS/MP, NT-MP/SS, CT-S/M and CE, respectively, were 3.47, 2.29, 4.87 and 0.26 kg ha-1. A correlation between N2O fluxes and the environmental variables was observed, with the exception of water-filled pore space (WFPS), but N2O peaks were associated with WFPS values of >65%. In the 2014-2015 growing season, yield-scaled N2O emissions from NT-MP/SS were lower than from CT-S/M. A multi-factor approach indicated that conventional management with main season soybean or maize and no alternating crop sequence intensifies soil N2O emissions in the Cerrado.

Nitrogen use efficiency-a key to enhance crop productivity under a changing climate.

Nitrogen (N) is an essential element required for the growth and development of all plants. On a global scale, N is agriculture's most widely used fertilizer nutrient. Studies have shown that crops use only 50% of the applied N effectively, while the rest is lost through various pathways to the surrounding environment. Furthermore, lost N negatively impacts the farmer's return on investment and pollutes the water, soil, and air. Therefore, enhancing nitrogen use efficiency (NUE) is critical in crop improvement programs and agronomic management systems. The major processes responsible for low N use are the volatilization, surface runoff, leaching, and denitrification of N. Improving NUE through agronomic management practices and high-throughput technologies would reduce the need for intensive N application and minimize the negative impact of N on the environment. The harmonization of agronomic, genetic, and biotechnological tools will improve the efficiency of N assimilation in crops and align agricultural systems with global needs to protect environmental functions and resources. Therefore, this review summarizes the literature on nitrogen loss, factors affecting NUE, and agronomic and genetic approaches for improving NUE in various crops and proposes a pathway to bring together agronomic and environmental needs.

The use of double-cropping in combination with no-tillage and optimized nitrogen fertilization reduces soil N2O emissions under irrigation.

The irrigation systems of the Ebro valley can lead to high N2O emissions. The effects that crop diversification, such as double-cropping in combination with conservation tillage and different N fertilizer ratios, has on soil N2O emissions have not been extensively studied in this region. The goal of this research was to measure N2O soil emissions and determine the tillage practices and N fertilization rates that provide the lowest emissions when combined with double-cropping systems. The work compared monocropping maize (MC) versus legume-maize double-cropping (DC) with two tillage systems (conventional tillage, CT; and no-tillage, NT), and three mineral N fertilization rates (zero, medium and high). Pea for grain (2019), vetch for green manure (2020), and vetch for forage (2021) were the legumes employed. The N2O emissions ranged from 0 to 15.5 mg N2O-N m-2 d-1 and were concentrated in the fertilization periods. Soil temperature and water filled pore space (WFPS) content significantly influenced soil N2O emissions. For both cropping systems, the conditions with the highest N2O emissions were soil temperatures above 20 °C and a WFPS of 50-60 %. The use of legumes facilitated reduced N fertilization in DC without affecting crop yield and led to reduced N2O emissions in this cropping system. DC reduced the emission factor (EF), which in all cases was lower than the default IPCC EF (1 %). With DC, a medium N fertilization rate produced similar yields to the high rate commonly applied by farmers, and also entailed lower N2O emissions. The no-tillage system, although producing higher levels of N2O, achieved lower yield-scaled N2O emissions due to greater crop yields. This work underlines the advantages of using double-cropping no-tillage systems combined with medium rates of N fertilization to reduce soil N2O emissions.

Soil aggregation and associated organic matter under management systems in sandy-textured soils, subtropical region of Brazil.

Increasing the diversity of plant species in agricultural production areas favors the maintenance or improvement of soil quality, particularly for soils with a sandy texture. This beneficial effect is related to the formation of aggregates of different origins. This study aimed to (i) verify whether soil use and management affect the proportion of biogenic (Bio) and physicogenic (Phy) aggregates and (ii) verify whether biogenic aggregation is more likely to lead to soil improvement than physicogenic aggregation. Three management systems were evaluated (permanent pasture, PP; no-tillage system, NT; and no-tillage + Brachiaria system, NT + B) as well as a reference area (Atlantic Forest biome vegetation, NF). According to their origin or formation pathway, the aggregates were separated, identified, and classified as Bio (formed by biological processes) and Phy (resulting from chemical and physical actions). The differentiation between Bio and Phy aggregates was performed based on the visualization of morphological features, such as shape, size, presence of roots, porosity, and subunit arrangements, and junctions. Only the PP area was able to promote greater aggregate formation of biological origin, with greater amounts of Bio aggregates. The highest total organic carbon (TOC) contents and the least negative δ13C values were also quantified in the aggregates of the PP area. The NT + B system provided an increase in the TOC content of its aggregates in comparison with aggregates in the NT and NF areas. Among the formation pathways, the Bio aggregates had the highest TOC and soil organic matter fractions contents and the most negative δ13C values. Perennial forage grasses vegetation was more important than the plant species diversity in favoring Bio aggregate formation. The beneficial effect of Brachiaria can be observed when incorporated as part of intercropping with corn in grain production systems. The biogenic aggregates favored the concentration of more labile soil organic matter fractions. The results of this study can provide important theoretical information for future studies focused on the combination of different plant species in agricultural food production areas on sandy-textured soils.

Arbuscular mycorrhizal fungi in the soil using cover crops with and without nitrogen addition.

This study aimed to evaluate the occurrence of mycorrhizal fungi and glomalin content in soil under different cover crops with and without the application of nitrogen in the cover. The following cover plants were used: Crotalaria juncea (Crotalaria juncea L.), wild beans from Ceará (Canavalia brasiliensis Mart. ex Benth.), Guandú 'BRS mandarin' [Cajanus cajan (L.) Millsp.], millet 'BR05' [Pennisetum glaucum (L.) R.Br.] and sorghum 'BR 304' [Sorghum bicolor (L.) Moench]. The absolute control of the experiment was the treatment without the use of cover crops, that is, the vegetation of spontaneous occurrence in the area. The experimental design was randomized blocks in subplots with three replications. Spore density, mycorrhizal colonization rate, easily extractable glomalin, and species present in the rhizosphere of the cover crops were determined. No differences were found in the diversity of mycorrhizal fungi associated with the different cover crops studied or in the values of spore density, root colonization, or glomalin content. Nitrogen application did not influence the mycorrhizal activity in the investigated cover crops. The most frequent species associated with cover crops were Scutellospora pellucida and Scutellospora persica in C. juncea; Gigaspora sp. on Sorghum; Glomus macrocarpum in Guandu; G. macrocarpum and Glomus clavisporum in millet; and Glomus microaggregatum and Glomus tortuosum in Spontaneous Vegetation.

Soil Pore Network Complexity Changes Induced by Wetting and Drying Cycles-A Study Using X-ray Microtomography and 3D Multifractal Analyses.

Soils are dynamic and complex systems in their natural state, which are subjected to profound changes due to management. Additionally, agricultural soils are continuously exposed to wetting and drying (W-D) cycles, which can cause modifications in the complexity of their pores. Thus, we explore how successive W-D cycles can affect the pore network of an Oxisol under contrasting managements (conventional tillage-CT, minimum tillage-MT, no tillage-NT, and secondary forest-F). The complexity of the soil pore architecture was evaluated using a 3D multifractal approach combined with lacunarity, Shannon's entropy, and pore geometric parameters. Our results showed that the multifractal approach effectively identified and quantified the changes produced in the soil pore architecture by the W-D cycles. The lacunarity curves revealed important aspects of the modifications generated by these cycles. Samples under F, NT, and MT suffered the most significant changes. Pore connectivity and tortuosity were largely affected by the cycles in F and NT. Our findings demonstrated that the 3D geometric parameters and normalized Shannon's entropy are complementary types of analysis. According to the adopted management, they allowed us to separate the soil into two groups according to their similarities (F and NT; CT and MT).

Influence of Agronomic Factors on Mycotoxin Contamination in Maize and Changes during a 10-Day Harvest-Till-Drying Simulation Period: A Different Perspective.

Agronomic factors can affect mycotoxin contamination of maize, one of the most produced cereals. Maize is usually harvested at 18% moisture, but it is not microbiologically stable until it reaches 14% moisture at the drying plants. We studied how three agronomic factors (crop diversification, tillage system and nitrogen fertilization rate) can affect fungal and mycotoxin contamination (deoxynivalenol and fumonisins B1 and B2) in maize at harvest. In addition, changes in maize during a simulated harvest-till-drying period were studied. DON content at harvest was higher for maize under intensive tillage than using direct drilling (2695 and 474 µg kg-1, respectively). We found two reasons for this: (i) soil crusting in intensive tillage plots caused the formation of pools of water that created high air humidity conditions, favouring the development of DON-producing moulds; (ii) the population of Lumbricus terrestris, an earthworm that would indirectly minimize fungal infection and mycotoxin production on maize kernels, is reduced in intensive tillage plots. Therefore, direct drilling is a better approach than intensive tillage for both preventing DON contamination and preserving soil quality. Concerning the simulated harvest-till-drying period, DON significantly increased between storage days 0 and 5. Water activity dropped on the 4th day, below the threshold for DON production (around 0.91). From our perspective, this study constitutes a step forward towards understanding the relationships between agronomic factors and mycotoxin contamination in maize, and towards improving food safety.

Modeling the effects of farming management practices on soil organic carbon stock under two tillage practices in a semi-arid region, Morocco.

Farming management practices are of paramount importance for soil organic carbon (SOC) sequestration in carbon (C) cycling at different scales. However, due to a lack of proper methodologies, estimating the impacts of different soil management practices on overall SOC stock remains inadequately quantified. In this paper, a process-based model, Denitrification-Decomposition (DNDC), was validated on midterm (9 years) and employed depending on the local climate, soil and management conditions, to assess the impacts of alternative management practices on SOC stock under two tillage systems, in a semi-arid region of Morocco. Validated results showed a good agreement between model simulated and observed values, based on the normalized root mean square error (RMSE) and Pearson correlation coefficient (r). This agreement indicates that the DNDC model could capture patterns and magnitudes changes across the climate zone, soil type, and management practices. Modeled results pointed out that, under no-tillage practice (NT), the SOC content increased by 30% compared to conventional tillage (CT). During the simulated period (9 years), the SOC sequestration potential (CSP) has been greatly improved with increased crop residue rate and application of farmyard manure (FY-manure). This increase ranged from 415 kg C/ha to 1787 kg C/ha under NT practice, and from 150 kg C/ha to 818 kg C/ha under CT system. In contrast, increasing fertilizer rate had low to negligible effect on SOC stock. On the other hand, CSP declined by 107-335 kg C/ha and by 177-354 kg C/ha under NT and CT practices respectively, when decreasing N-fertilizer rates. In light of these results, an increase in crop residue rate returned at surface after harvest and application of organic fertilizer, especially under NT practice, can substantially improve SOC stock in a semi-arid region.

Tillage systems as a function of greenhouse gas (GHG) emission and fuel consumption mitigation.

In order to investigate the possibility of reducing GHG in winter wheat production, field trial was set up in a 3-year experiment (VS) with four different tillage systems (TS) and three N fertilization norms (FN). The tillage systems were CT-conventional tillage, DT-disk harrowing, LT-soil loosening, and NT-no tillage system. N fertilization norms were set to 120, 150 and 180 kg ha-1. Fuel consumption was measured with three-channel valve, and total value of consumption was calculated on total machinery passes according to technological map. Calculation of greenhouse gas (GHG) emissions from winter wheat production were done by BioGrace model (version 4d 2015). GHG emission per ton of yearly raw material was calculated from fertilizers (production and field emissions), seed, plant protection and diesel usage, so the result was expressed in kg CO2eq ha-1 per year. The main properties of research (TS, FN and VS) are showing statistical significance on total GHG emission from winter wheat production. The largest GHG emission had LT tillage system with 261.89 kg CO2eq ha-1 from fuel emission and 2919.22 kg CO2eq ha-1 in total. This tillage system also had highest yield of 7.78 t ha-1. The lowest yield was observed at NT system (6.92 t ha-1), also with the lowest GHG emission from fuel consumption and total production (fuel 118.30 and total 2685.94 kg CO2eq ha-1). Reduced tillage system such as DT can significantly reduce GHG emissions from diesel consumption without having an impact on wheat yield. This study suggests that DT, primarily, and NT can be recommended as convenient agricultural practices conducive to reconstruct an optimal balance between GHG emissions, yields, and N excesses.

Residue retention promotes soil carbon accumulation in minimum tillage systems: Implications for conservation agriculture.

Crop residue retention and minimum tillage (including no-tillage, NT, and reduced tillage, RT) are common conservation tillage practices that have been extensively applied for improving soil health and reducing the negative environmental impact caused by intensive farming. However, the effects of minimum tillage, coupled with crop residue retention (including no-tillage plus residue retention, NTR, and reduced tillage plus residue retention, RTR), on soil organic carbon (SOC) stock have not been systematically analyzed. Using a dataset consisting of 1928 pairs of data points from 243 studies, we conducted a global meta-analysis to evaluate the effects of crop residue retention and minimum tillage on SOC stock in the 0-30 cm soil and how these effects varied with soil (soil sampling depth and texture), environmental (climate) and crop management conditions (cropping intensity), as well as treatment duration. We found that regardless of the climatic condition, crop management, or residue retention, minimum tillage alone increased the overall mean SOC stock. Specifically, NT and RT increased SOC stock by 11 and 6%, respectively, in comparison to conventional tillage (CT). Compared with CT, NTR and RTR increased SOC stock by 13 and 12%, respectively. The above effects were greater in the topsoil (62% of data points from the 0-15 cm depth) than in the subsoil (38% of data points from the 15-30 cm depth). Moreover, residue retention enhanced the resistance of SOC turnover to agricultural and environmental factors; mean annual temperature (coefficient = 0.15), soil pH (0.14), and experimental duration (0.08) were critical for increasing SOC stock with minimum tillage alone, while the response ratio of SOC stock under coupled residue retention and minimum tillage was insensitive to changes in those factors. Additionally, double cropping generally increased SOC stock cross all conservation tillage practices compared to multiple cropping. Therefore, we conclude that minimum tillage coupled with residue retention in a double-cropping system is the most promising management system for increasing SOC stocks in the 0-30 cm soil in croplands Our finding can inform sustainable soil management practices aimed at increasing resistance of SOC in croplands to climate change and soils degradation induced by intensive agriculture.

Long-term no-tillage application increases soil organic carbon, nitrous oxide emissions and faba bean (Vicia faba L.) yields under rain-fed Mediterranean conditions.

The introduction of legumes into crop sequences and the reduction of tillage intensity are both proposed as agronomic practices to mitigate the soil degradation and negative impact of agriculture on the environment. However, the joint effects of these practices on nitrous oxide (N2O) and ammonia (NH3) emissions from soil remain unclear, particularly concerning semiarid Mediterranean areas. In the frame of a long-term field experiment (23 years), a 2-year study was performed on the faba bean (Vicia faba L.) to evaluate the effects of the long-term use of no tillage (NT) compared to conventional tillage (CT) on yield and N2O and NH3 emissions from a Vertisol in a semiarid Mediterranean environment. Changes induced by the tillage system in soil bulk density, water filled pore space (WFPS), organic carbon (TOC) and total nitrogen (TN), denitrifying enzyme activity (DEA), and bacterial gene (16S, amoA, and nosZ) abundance were measured as parameters potentially affecting N gas emissions. No tillage, compared with CT, significantly increased the faba bean grain yield by 23%. The tillage system had no significant effect on soil NH3 emissions. Total N2O emissions, averaged over two cropping seasons, were higher in NT than those in CT plots (2.58 vs 1.71 kg N2O-N ha-1, respectively; P < 0.01). In addition, DEA was higher in NT compared to that in CT (74.6 vs 18.6 µg N2O-N kg-1 h-1; P < 0.01). The higher N2O emissions in NT plots were ascribed to the increase of soil bulk density and WFPS, bacteria (16S abundance was 96% higher in NT than that in CT) and N cycle genes (amoA and nosZ abundances were respectively 154% and 84% higher in NT than that in CT). The total N2O emissions in faba bean were similar to those measured in other N-fertilized crops. In conclusion, a full evaluation of NT technique, besides the benefits on soil characteristics (e.g. TOC increase) and crop yield, must take into account some criticisms related to the increase of N2O emissions compared to CT.

Health risk assessment and soil and plant heavy metal and bromine contents in field plots after ten years of organic and mineral fertilization.

Heavy metals and bromine (Br) derived from organic and industrialized fertilizers can be absorbed, transported and accumulated into parts of plants ingested by humans. This study aimed to evaluate in an experiment conducted under no-tillage for 10 years, totaling 14 applications of pig slurry manure (PS), pig deep-litter (PL), dairy slurry (DS) and mineral fertilizer (MF), the heavy metal and Br contents in soil and in whether the grains produced by corn (Zea mays L.) and wheat (Triticum aestivum L.) under these conditions could result in risk to human health. The total contents of As, Cd, Pb, Cr, Ni, Cu, Zn and Br were analyzed in samples of fertilizers, waste, soil, shoots and grains of corn and wheat. Afterwards, enrichment factor (EF), accumulation factor (AF), health risk index (HRI), target hazard quotient (THQ) and target cancer risk (TCR) were determined. Mineral fertilizer exhibited the highest As and Cr content, while the highest levels of Cu and Zn were found in animal waste. The contents of As, Cd, Cr, Cu, Ni, Pb and Zn in soil were below the limits established by environmental regulatory agencies. However, a significant enrichment factor was found for Cu in soil with a history of PL application. Furthermore, high Zn contents were found in shoots and grains of corn and wheat, especially when the plants were grown in soil with organic waste application. Applications of organic waste and mineral fertilizer provided high HRI and THQ for Br and Zn, posing risks to human health. The intake of corn and wheat fertilized with pig slurry manure, swine deep bed, liquid cattle manure and industrialized mineral fertilizer did not present TCR.

Management systems and soil use on fractions and stocks of organic carbon and nitrogen total in cerrado latosol / Sistemas de manejo e uso do solo sobre as frações e estoque de carbono e nitrogênio em latossolo de cerrado

Cerrado areas are agricultural frontiers of Brazil, being important to know the dynamics of carbon and nitrogen in agricultural production systems. The objective of this study was to evaluate the effects of management and soil use in fractions and stocks organic carbon and nitrogen in the Cerrado soil. The experiment was conducted in Latosol with four treatments: native Cerrado (CE), no-tillage 18 years (NT), coffee 10 years (CF) and integrated system for agriculture (ISA) three years, evaluating the fractions and stocks of organic carbon and nitrogen in three depths. Soil management systems, at all depths, were not able to recover the organic carbon, nitrogen and their stocks in relation to the Cerrado. In the surface layer there was a decrease in the organic carbon content of 21, 33 and 46% for NT, CF and ISA respectively. Also there was a reduction in the nitrogen content in the surface layer of 33, 36 and 59% for the NT, CF and ISA respectively. Organic carbon varied from 74.3 Mg ha-1 in the CE, 58.8 Mg ha-1 in NT, 56.4 Mg ha-1 in CF and 50.8 Mg ha-1 in ISA. It was concluded that the total organic carbon, nitrogen and its fractions were effective in demonstrating the effects of managements and soil use; that of no-tillage and coffee were not efficient in the recovery of stocks of carbon and nitrogen requiring managements with more carbon input and the integrated production system is still in consolidation process.

Áreas de cerrado são fronteiras agrícolas do Brasil, sendo importante conhecer a dinâmica do carbono e nitrogênio em sistemas de produção agrícola. O objetivo deste estudo foi avaliar os efeitos do manejo e uso do solo em frações e estoques de carbono orgânico e nitrogênio em solo de Cerrado. O experimento foi realizado em Latossolo Vermelho com quatro tratamentos: Cerrado nativo (CE), plantio direto 18 anos (PD), área com café 10 anos (CF) e sistema integrado de produção agropecuária (SIPA) 3 anos avaliando as frações e estoques de carbono orgânico e nitrogênio em três profundidades. Os sistemas de manejo do solo, em todas as profundidades, não foram capazes de recuperar o teor carbono orgânico, nitrogênio e seus estoques em relação ao Cerrado. Na camada superficial houve diminuição no teor de carbono orgânico de 21, 33 e 46% para PD, CF e SIPA, respectivamente. Também verificou-se redução no teor de nitrogênio na camada superficial de 33, 36 e 59% para o PD, CF e SIPA, respectivamente. Os estoques de carbono orgânico variaram de 74,3 Mg ha-1 no CE, 58,8 Mg ha-1 no PD, 56,4 Mg ha-1 no CF e 50,8 Mg ha-1 no SIPA. Conclui-se que o carbono orgânico total, nitrogênio e suas frações foram eficientes para demonstrar os efeitos dos manejos e uso do solo; que os sistemas de PD e CF não foram eficientes na recuperação dos estoques de carbono e nitrogênio necessitando de manejos com maior entrada de carbono e que SIPA ainda esta em processo de consolidação.

Acúmulo de nutrientes e tempo de decomposição da palhada de espécies forrageiras em função de épocas de semeadura / Nutrients accumulation and straw decomposition time of forage species in function of sowing times

Com o intuito de identificar o potencial produtivo das espécies forrageiras Sorghum bicolor (L.) Moench, Pennisetum glaucum (L.) R. Br. e Urochloa brizantha cv. Xaraés em função de épocas de semeadura, bem como, a posterior formação de palhada para continuidade do sistema plantio direto, avaliou-se a produtividade de massa seca, a relação C/N e lignina/N total, o acúmulo de nutrientes e a decomposição da palhada em duas safras agrícolas. O experimento foi realizado em Selvíria - MS (20°18'S e 51°22'W, com altitude de 370 m), num LATOSSOLO VERMELHO Distroférrico. O delineamento utilizado foi o de blocos casualizados, em arranjo fatorial 3 x 3, com três espécies de plantas forrageiras: sorgo forrageiro (Sorghum bicolor (L.) Moench), milheto (Pennisetum glaucum (L.) R. Br.) e o capim xaraés (Urochloa brizantha cv. Xaraés) e três épocas de semeadura (1ª época - 14/09/09 (E1), 2ª época - 29/09/09 (E2) e 3ª época - 14/10/09 (E3), manejadas aos 45 dias após emergência - DAE), com 4 repetições. Para o segundo ano agrícola (2010/2011), utilizaram-se as mesmas espécies forrageiras e delineamento experimental, com as seguintes épocas de semeadura: 1ª época - 10/09/10 (E1), 2ª época - 27/09/10 (E2) e 3ª época - 20/10/10 (E3), respectivamente. As maiores produtividades de massa seca e acúmulos de nutrientes foram obtidos pela cultura do sorgo forrageiro nas três épocas de semeadura. A cultura do sorgo forrageiro apresentou os maiores valores da relação C/N e lignina/N total, principalmente nas 2ª e 3ª épocas, nos dois anos agrícolas, proporcionando menor degradação da palhada em comparação ao milheto e ao capim xaraés. A decomposição da palhada foi mais lenta para o sorgo forrageiro e o milheto. Independentemente da espécie forrageira e da época de semeadura, a deposição inicial de massa seca das forrageiras foram adequadas para utilização destas espécies no sistema plantio direto, nas condições climáticas de cerrado de baixa altitude.

In order to identify the productive potential of the forages Sorghum bicolor (L.) Moench, Pennisetum glaucum (L.) R. Br and Urochloa brizantha cv. Xaraés due to sowing times, as well as the subsequent formation of straw for no tillage system continuity, evaluated the dry mass production, the relation of C/N and lignin/N total, the nutrients accumulation and straw decomposition in two agricultural seasons. The experiment was conducted in Selvíria - MS (20° 18' S and 51° 22' W, with an altitude of 370 m), in a Dark Red Dystrophic Latosol. A randomized block design was adopted in a 3 × 3 factorial scheme consisting of three species of forage plants: sorghum (Sorghum bicolor (L.) Moench), pearl millet (Pennisetum glaucum (L.) R. Br ) and grass xaraés (Urochloa brizantha cv. Xaraés) and three sowing times (1st season - 09.14.09 (E1), 2nd season - 09.29.09 (E2) and 3rd season - 10.14.09 (E3), managed 45 days after emergence - DAE), with 4 replications. For the second growing season (2010/2011), was used the same forages species and experimental design, with the following sowing times: 1st season - 09.10.10 (E1), 2nd season - 09.27.10 (E2) and 3rd season - 10.20.10 (E3), respectively. The highest yield dry mass and nutrient accumulation were obtained by the forage sorghum culture in the three sowing times. The forage sorghum culture presented the highest values of C/N and lignin/N total, mainly in the 2nd and 3rd seasons, in both years, providing less straw degradation compared to pearl millet and xaraés grass. The straw decomposition was slower for the forage sorghum and pearl millet. Regardless of forage species and sowing time, the initial dry mass deposition of forage species were suitable for these species in the no tillage system, in climatic conditions of of low altitude cerrado.

Abundância natural de δ 13C e δ 15N em sistemas de manejo conservacionista no cerrado / Natural abundance of δ 13C and δ 15N in management systems conservation in the cerrado

Diferentes sistemas de uso e manejo do solo modificam o sinal isotópico do 13C e 15N do solo. O objetivo deste trabalho foi avaliar a abundância natural de 13C e 15N no perfil do solo em áreas com diferentes sistemas de uso do solo no Cerrado goiano. Foram avaliados dois sistemas com rotação de culturas: integração lavourapecuária - ILP (milho+braquiária/feijão/algodão/soja) e sistema plantio direto - SPD (girassol/milheto/soja/milho). Uma área de Cerrado natural (Cerradão) foi tomada como condição original do solo. Foram coletadas amostras de solo nas camadas de 0,0-10,0; 10,0-20,0; 20,0-30,0; 30,0-40,0; 40,0-50,0; 50,0-60,0; 60,0-80,0 e 80,0-100,0 cm e mensurados o 15N e 13C do solo por meio de espectrômetro de massa. Em relação ao 13C, verificou-se predomínio de plantas C3 no Cerrado e influência das plantas C4 nas áreas de SPD e ILP. Os valores de 15N apresentaram um enriquecimento isotópico de acordo com o aumento da profundidade, com maiores valores de 15N observados nas áreas cultivadas. A substituição da vegetação original de Cerradão para implantação de SPD e ILP acarretou mudanças no sinal 13C, ou seja, após 17 anos de cultivo, a incorporação de carbono das gramíneas nestas áreas proporcionou um aumento do sinal de 13C. A análise isotópica de 15N indicou maior mineralização da matéria orgânica do solo com o aumento da profundidade do solo e com maiores taxas nas áreas cultivadas.

Different land use systems and soil management modify the isotopic signal of soil 13C and 15N. The objective of this study was to evaluate the natural abundance the 13C and 15N in the soil profile in areas with different land use systems in the Cerrado of Goias State, Brazil. We evaluated two systems with crop rotation: croplivestock integration - CLI (corn + brachiaria/beans/cotton/soybean) and no-tillage system - NTS (sunflower/millet/soybean/corn). An area of natural Cerrado (Cerradão) was taken as the original condition of the soil. Soil samples were collected in layers of 0.0 to 10.0, 10.0 to 20.0, 20.0 to 30.0, 30.0 to 40.0, 40.0 to 50.0, 50.0 to 60.0, 60.0 to 80.0 and 80.0 to 100.0 cm, and the measured the 15N and 13C of the soil by mass spectrometer. Regarding 13C, it was found predominantly in the C3 plant Cerrado influence plant and C4 in the areas of NTS and CLI. The values presented 15N an isotopic enrichment according to the increase in depth, with higher values of 15N observed in cultivated areas. The replacement of the original vegetation of Cerrado for implantation of NTS and CLI led to changes in 13C, i.e., after 17 years of cultivation, the incorporation of carbon from grasses in these areas resulted in an increase in 13C signal.. Isotopic analysis of 15N indicated greater mineralization of soil organic matter with increasing soil depth and with higher rates in cultivated areas.

Frações granulométricas e oxidáveis de matéria orgânica sob diferentes sistemas de uso do solo, no Paraná, Brasil / Granulometric and oxidizable fractions of organic matter under different land use systems in the state of Paraná, Brazil

Neste estudo objetivou-se quantificar o carbono orgânico total (COT), o carbono das frações granulométricas e oxidáveis da matéria orgânica do solo (MOS) em áreas sob diferentes sistemas de uso do solo, em Marmeleiro-PR. Foram coletadas amostras de terra nas camadas de 0-5, 5-10, 10-20 e 20-40 cm, sendo nestas quantificados os teores de COT, carbono orgânico particulado (COp), carbono orgânico associado aos minerais (COam) e o carbono das frações oxidáveis (F1, F2, F3, F4 e F1/F4). O sistema de semeadura direta (SSD) apresentou maiores valores de COT (0-5 cm) e o sistema de plantio convencional (SPC), os menores (0-5 e 5-10 cm). O SSD e a área de pastagem apresentaram maiores teores de COp (0-5 cm). No SPC verificaram-se os menores teores de COp em superfície e maiores em profundidade. Os menores teores de carbono das frações oxidáveis foram encontrados no SPC (0-10 cm). O SSD aumenta os teores de COT, COp e carbono oxidável (F1 e F4) na camada superficial quando comparado com o SPC. Este acarreta em teores de COT iguais aos da área de SSD em profundidade e ocasiona a diminuição dos teores de COam e do carbono oxidável da fração F4 em todas as profundidades avaliadas. Por meio da relação F1/F4 pode-se inferir que o SPC desfavorece o equilíbrio das frações F1 e F4, enquanto o SSD acarreta em valores similares aos das áreas sem interferência antrópica. As frações granulométricas e oxidáveis da MOS são eficientes para identificar mudanças ocasionadas no solo pelo manejo.

This study aimed to quantify the total organic carbon (TOC), granulometric and oxidizable carbon fractions of soil organic carbon (SOM) in areas under different land use in Marmeleiro, Paraná State, Brazil. We collected soil samples in the 0-5, 5-10, 10-20 and 20-40 cm, and being these quantified to TOC, particulate organic carbon (POC), organic carbon associated minerals (OCam) and carbon fractions oxidizable (F1, F2, F3, F4 and F1/F4). The notillage system (NTS) had higher TOC values (0-5 cm) and the conventional tillage system (CTS), the lowest (0-5 and 5-10 cm). The NTS and the grazing area had higher concentrations of POC (0-5 cm). In the CTS there were the lowest levels of POC in surface and greater depth. The lower carbon content of oxidizable fractions were found in the CTS (0-10 cm). The NTS increase the TOC, and POC oxidisable carbon (F1, F4) in the surface layer when compared to the CTS. This leads to TOC area equal to the NTS in depth and leads to decreased amounts of carbon and OCam oxidizable fraction F4 in all experiments. Through the F1/F4 ratio can be inferred that the CTS disfavors the balance of fractions F1 and F4, while the NTS leads to values similar to those in areas without human interference. The granulometric and oxidizable fractions of SOM are efficient to identify changes in soil caused by management.

Desempenho agronômico da cultura do milho e espécies forrageiras em sistema de Integração Lavoura-Pecuária no Cerrado / Agronomic performance of corn and forages species in Crop-Livestock Integration system in the Cerrado

O consórcio entre culturas leva à competição por fatores de produção como água, luz e nutrientes, porém, atualmente, é comum o cultivo integrado do milho com forrageiras para recuperação e renovação de pastagens degradadas, diversificação na renda dos produtores e produção de massa seca para sustentabilidade da agricultura. O objetivo deste trabalho foi avaliar o desempenho agronômico e o teor de nitrogênio da cultura do milho consorciado com forrageiras dos gêneros Panicum e Brachiaria. O delineamento experimental foi o de blocos casualizados, com quatro repetições. O experimento foi constituído de oito tipos de consórcio do milho com: Panicum maximum cv. 'Tanzânia', semeado simultaneamente (MTS) ou por ocasião da adubação nitrogenada de cobertura do milho (MTC); Panicum maximum cv. 'Mombaça', semeado simultaneamente (MMS) ou por ocasião da adubação nitrogenada de cobertura (MMC); Brachiaria brizantha cv. 'MG-5', semeado simultaneamente (MBS) ou por ocasião da adubação nitrogenada de cobertura (MBC); Brachiaria ruziziensis, semeado simultaneamente (MRS) ou por ocasião da adubação nitrogenada de cobertura (MRC), além do cultivo do milho sem consorciação (MSC). Quando a cultura do milho atingiu o estádio V6, procedeu-se à adubação de cobertura com 100kg ha-1 de N para os 9 tratamentos. Os consórcios de forrageiras dos gêneros Panicum e Brachiaria com o milho não afetam o teor N foliar, os componentes de produção e a produtividade de grãos de milho, quando comparados com o cultivo solteiro. As maiores produtividades de massa seca das forrageiras foram nos consórcios semeados na ocasião da adubação nitrogenada de cobertura do milho.

The intercropped between cultures lead to competition for production factors such as water, light and nutrients, however currently is common for integrated cultivation of corn for forage recovery and renovation of degraded areas, diversification of the producers income and production of dry matter for no-tillage system. The objective of this work was to evaluate the agronomic performance and nitrogen content of corn intercropped with forage of the genuse Brachiaria and Panicum. The experimental design was a randomized complete block with four repetitions. The experiment consisted of eigth treatments types of corn intercropped with: Panicum maximum cv. 'Tanzania' sowed simultaneously (MTS) or for occasion of the nitrogen fertilization at covering (TCM); Panicum maximum cv. 'Mombaça' sowed simultaneously (MMS) or for occasion of the nitrogen fertilization at covering (MMC); Brachiaria brizantha cv. 'MG-5' sowed simultaneously (MBS) or for occasion of the nitrogen fertilization at covering (MBC); Brachiaria ruziziensis sowed simultaneously (MRS) or for occasion of the nitrogen fertilization at covering (MRC), besides the corn without intercropping (MSC). When the corn reached the V6 stage, proceeded the fertilization at covering with 100kg ha-1 N for the 9 treatments. The intercropped of forage of the genuse Brachiaria and Panicum with corn did not affect the N leaf content, yield components and grain yield in relation to corn cropping. The highest dry matter yields of the forages were in the consortium sown at the occasion of the corn nitrogen fertilization at covering.

Atributos físicos do solo e produtividade da soja em sistema de integração lavoura-pecuária com braquiária e soja / Soil physical attributes and soybean production in a crop-livestock integration system with Brachiaria sp and Glycine max

A integração lavoura-pecuária por meio da sucessão entre pastagem de braquiária no outono/inverno e culturas de grãos no verão constitui-se em uma opção para aumentar e diversificar a renda do produtor e melhorar a qualidade do sistema plantio direto. Com o objetivo de avaliar o efeito da época de dessecação da pastagem ou da pressão de pastejo por bovinos sobre atributos físicos do solo e a produtividade da soja em um sistema de integração lavoura-pecuária (SILP), foi conduzido um experimento sobre um Latossolo Vermelho Distroférrico. Nas parcelas principais, foram aplicadas pressões de pastejo equivalentes a 6,9; 9,4; e 16,5 unidades animais por hectare durante 19 dias em pastagem de Brachiaria brizantha cv. 'Xaraes', cuja fitomassa foi dessecada 30 dias antes da semeadura da soja (DAS). Também foram conduzidos tratamentos sem pastejo, nos quais a fitomassa foi dessecada aos 30, 44 e 52DAS. Foi determinada a fitomassa remanescente da pastagem, densidade, porosidade e resistência à penetração do solo e a produtividade das cultivares de soja 'BRS 294RR' e 'BRS 255RR', semeadas em subparcelas. As alterações nos atributos físicos do solo pelo pisoteio se concentraram na camada de 0,0-0,05m, contudo as maiores pressões de pastejo aumentaram o grau de compactação do solo até a camada de 0,2-0,3m. A produtividade da cultivar 'BRS 294RR' aumentou e a da cultivar 'BRS 255RR' não foi afetada pelo incremento da pressão de pastejo, demostrando que há diferença de resposta entre os genótipos ao grau de compactação do solo e, principalmente, à fitomassa remanescente da pastagem. A produtividade da soja em SILP com alta produção de matéria seca de B. brizantha é afetada pelo intervalo entre a dessecação da pastagem e a semeadura da cultura.

Crop livestock integration systems (CLIS) involving pastures of Brachiaria brizantha in autumn/winter and soybeans in summer have been considered an option to increase and diversify crop production and improve no-tillage system. This work aimed to evaluate the effect of grass desiccation timings or cattle grazing pressures on soil physical attributes and soybean yields in a crop-livestock integration system. The experiment was carried out on a dark red Latosol (Rhodic Eutrudox, US Soil Taxonomy) in southern Brazil. In the major plots, grazing pressures of 6.9, 9.4, and 16.5 animal unities per hectare were applied during 19 days to a pasture of Brachiaria brizantha cv. 'Xaraes', which phytomass was desiccated 30 days before soybean sowing (DBS). Ungrazed plots were desiccated 30, 44 and 52 DBS. Remaining phytomass of the pasture; soil bulk density, porosity and soil resistance to penetration; and yield of soybean cultivars 'BRS 294RR' and 'BRS 255RR' (sowed in subplots), were determined. Changes in soil physical attributes by animal trampling were concentrated on topsoil layer (0.0-0.05m), and soil compaction level was increased by the highest grazing pressure down the 0.2-0.3 layer. The yield of soybean cv. 'BRS 294RR' was increased with rising grazing pressures, whereas the yield of soybean cv. 'BRS 255RR' was not affected, showing that soybean genotypes had different responses to soil compaction level and, mainly, to remaining phytomass of pasture. In CLIS with high production of B. brizantha dry mass, soybean yields are closely associated to time interval between grass desiccation and soybean planting.