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A study was conducted to understand the role of different soybean production systems and soil chemical and physical attributes on phytonematode population density in a physical model of production systems. In an area of 28 hectares, the following production systems were established 26 years ago: a) conventional system (CS) - succession of soybeans in summer and oats in winter, and continuous soil preparation with disc harrow; b) no-till system (NTS) - with rotation of summer crops (soybeans and corn) and winter crops (wheat, oats, and fodder radish); c) integrated crop-livestock system (ICLS) - conducted in no-till system and using Urochloa brizantha (cultivar Piatã) pasture, in crop-livestock rotation every two years; d) permanent pasture system (PP) - U. brizantha (cultivar Piatã) with beef cattle. Twenty six years after the systems were installed, soil samples were taken for nematological analysis and analysis of the soil's chemical and physical attributes. The results showed an almost absolute prevalence of the reniform nematode (Rotylenchulus reniformis, Rr) in the area. The PP system had the lowest population (average of 2 Rr/200cc), followed by the ICLS systems (average of 12 to 25 Rr/200cc). The highest population densities were observed in the CS system (1068 Rr/200cc) and the NTS system when soybeans were grown in the last two years before sampling (1361 Rr/200cc). The highest population densities of R. reniformis were associated with higher soil density in the arable layer, higher K and P levels in the soil, and lower organic matter contents.

Accelerated erosive processes are global threats that can be quantified and classified. The northern region of Paraná is known for its high grain yield and crop rotation (soybeans, corn, wheat and oats). The municipality of Bela Vista do Paraíso has the particularity of being located on two geological formations, a basic eruptive of the Serra Geral Formation (JKsg) and a sandstone of the Adamantina Formation (Ka). The use of GIS to quantify soil loss has been intensifying in earth sciences, in which the GISus-M software is relevant for its practicality. It was observed that the C factors, which in this case have their values determined by the methodology of Durigon et al. (2014), are linked to monthly soil loss due to erosion due to crop rotation and their fallow period, in addition to erodibility (K factor) also having its significance, mainly associated with LS factors. The use of monthly modeling for RUSLE expresses a better observation of the erosive processes that occur, in addition to contributing to soil conservation measures and the planning and ordering of local roads in the municipality. Keywords: erosion; RUSLE; geological formations; GISus-M. [ABSTRACT FROM AUTHOR]

Cover crops during the off-season and multifunctional microorganisms represent strategic technologies with potential to enhance the sustainability of soybean production. This study aimed to investigate the effects of cover crop mixes and the application of multifunctional microorganisms on the economic analysis, gas exchange, yield components and grain yield of soybean plants. The experimental design followed a randomized block pattern, in a 6 x 2 factorial arrangement, with four replications. The treatments consisted of six cover crop combinations [fallow (control); millet (Pennisetum glaucum) with crotalarias (Crotalaria juncea, C. spectabilis and C. ochroleuca); millet and pigeon pea (Cajanus cajanus); millet and Urochloa ruziziensis; millet, U. ruziziensis and pigeon pea; millet and buckwheat (Fagopyrum esculentum)], with or without the application of a Trichoderma asperellum pool. The combination of millet + U. ruziziensis and millet + U. ruziziensis + pigeon pea showed the highest dry matter production and yielded the greatest nutrients content in the straw, which could provide a reduction in fertilization for the following crop. The soybean plants cultivated after millet + U. ruziziensis and millet + U. ruziziensis + pigeon pea demonstrated elevated photosynthetic rates and improved the instantaneous water-use efficiency. The application of multifunctional microorganisms led to a 16 % increase in the photosynthetic rate of the soybean plants. The highest yield was achieved by the soybean plants cultivated in areas with millet + U. ruziziensis and millet + U. ruziziensis + pigeon pea. Moreover, the application of multifunctional microorganisms contributed to increase the pod count per meter, grains per pod, mass of 100 seeds and overall soybean grain yield.

ABSTRACT: The present study assessed the influence of the preceding crop (crotalaria or corn) on the bromatological, digestibility and microbiological aspects of the EMBRAPA 139 black oat hay (Avena strigosa) cultivar. A randomized block design was used, with subplots divided according to time, whereby the preceding crop (crotalaria or corn) was allocated to the main plot and hay storage times (baling, 30, 60 and 90 days of storage) to the subplots, with five repetitions. Crotalaria as predecessor resulted in lower indigestible fiber and higher protein contents in black oat hay, both in acid detergent, as well as higher pH. Corn as the preceding crop provided better hay digestibility due to lower neutral detergent insoluble protein content and higher in vitro neutral detergent fiber digestibility. The preceding crop did not significantly affect the drying time of forage and the microorganism population.

Cover crop species have been used in mixes in order to improve soil conditions; however, it is important to evaluate the relationship of the employed cultivars with phytonematodes to identify those that do not multiply the pathogens in the cultivated area. This study aimed to assess the response of 11 plant species used in cover crop mix to Meloidogyne enterolobii, M. incognita and Pratylenchus brachyurus. Six experiments were conducted in a greenhouse, using a completely randomized design, with five replications. BMX Potência RR soybean and Santa Clara tomato were used as controls. In at least one of the experiments, IPR 91 Baili buckwheat was susceptible (reproduction factor - RF ≥ 1) to M. enterolobii, M. incognita and P. brachyurus. Common white lupin, URS Altiva white oat, Iapar 61 (Ibiporã) black oat and Embrapa 139 (Neblina) black oat were susceptible to M. enterolobii and M. incognita and resistant (RF < 1) and/or immune (RF = 0) to P. brachyurus. IPR 89 rye and IPR 116 radish were found susceptible to M. incognita and P. brachyurus and resistant toM. enterolobii. BRS 1501 millet and Embrapa 29 (Garoa) black oat were susceptible to M. incognita and resistant/immune to M. enterolobii and P. brachyurus. Brachiaria ruziziensis was considered resistant to M. enterolobii and M. incognita and susceptible to P. brachyurus. URS Corona white oat was the only cover crop considered to be resistant and/or immune to all the nematode species evaluated.

ABSTRACT The objective was to study the adaptability and stability of soybean cultivars in the lowland production system under different conditions in a subtropical environment. Fourteen soybean cultivars were evaluated in five locations and three growing seasons in Rio Grande do Sul State, Brazil. Three sowing dates were evaluated in each location and growing season and named as: early, recommended for high yield and recommended to minimize the risk of water deficiency. The experiment was carried out in a randomized complete block design, with three replicates. Yield data was submitted to analysis of variance, and the Eberhart and Russel method was used to study its adaptability and stability. In general, the cultivars that showed adaptability and stability to the three sowing dates showed MG between 5.6 to 6.4 and the type of indeterminate growth. The cultivars A6411 RG, TEC 5936 IPRO and TECIRGA 6070 RR combined wide adaptability and stability, the cultivars Fundacep 65 RR and 6869 RSF RR presented high yield and stability of production and are recommended for lowland environments.

ABSTRACT With the recent discovery of five new species of the Monosporascus genus, a fungal genus involved in “Monosporascus root rot and vine decline,” pathogenicity studies have become important to understand the impact of these new species on cultivated plants, mainly on plant species used as an alternative for crop rotation. This study aimed to evaluate the pathogenicity of Monosporascus spp. in non-cucurbitaceous cultures. The tests were carried out in duplicate in a greenhouse in a completely randomized design, with the treatments: One isolate of each species of Monosporascus (M. brasiliensis, M. caatinguensis, M. cannonballus, M. mossoroensis, M. nordestinus, and M. semiaridus) and the absolute control, and five cultures (cowpea, jack bean, corn, sorghum, and bell pepper). Seeds of these cultures were sown in pots containing soil + Tropstrate HT® (ratio 2:1, v / v), previously inoculated with wheat seeds colonized with the species of Monosporascus. After 50 days of sowing, plants were evaluated for incidence, disease severity, length of shoot and roots, fresh and dry weight of shoots and roots. All inoculated Monosporascus species were able to induce damage in cowpea and bell pepper cultures, with M. cannonballus being the most aggressive. Corn, jack beans, and sorghum presented few or no symptoms of the disease and may be indicated as alternative cultures to be used in crop rotation with cucurbits. Studies with a greater number of isolates and cultivars for each culture tested in this study should be carried out to strengthen the data obtained.

ABSTRACT In Brazil, to conserve soil and water, the adoption of a complete array of conservation agriculture technologies in conjunction with contour farming and agricultural terraces is necessary. However, there is little knowledge about the awareness and adoption level of conservationist practices by farmers. In this context, the objective of the study, which took place in a watershed containing agricultural areas dominated by annual crops, was to verify farmers’ perception and adoption level of soil and water conservation practices and the relationship between their adoption level of conservation practices and their socioeconomic characteristics. For this purpose, a survey was carried out with farmers in the Rio Vermelho watershed in southern Brazil. It was found that the majority of farmers have adequate awareness about the use of soil and water conservation practices. Maintaining productivity was identified as the main reason to conserve soil and water, while reducing production costs and controlling erosion stood out as secondary reasons. Agricultural terraces and no-tillage were the most adopted practices by farmers. No-tillage was implemented by approximately 78.3% of landowners and 50% of tenants. However, only 26.8% of farmers adopted conservation agriculture. Overall, most farmers adopt conservationist practices, but in a partial manner, which may not be sufficient to ensure soil and water conservation. Awareness of soil and water conservation needs to be further improved.

The present study aimed to measure the technical and scale efficiency scores of agricultural establishments in the 35 intermediate regions of the Northeast of Brazil for the year 2017, which have the most up-to-date data. For this purpose, a two-stage model was used: the Data Envelopment Analysis (DEA) method, in Portuguese, Data Envelopment Analysis, with input orientation and the truncated normal Tobit. The results obtained by means of DEA revealed that the majority of the intermediate regions were fully efficient, both from the technical and scale points of view. Furthermore, by means of the truncated Tobit normal model, it can be inferred that fertilization, irrigation, access to financing, and regular high school education increase efficiency. Whereas, factors such as total area of establishments, technical assistance, crop rotation, and planting in contour lines, negatively affect efficiency in the segment. [ABSTRACT FROM AUTHOR]

Copyright of Desenvolvimento e Meio Ambiente is the property of Universidade Federal do Parana and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The culture of cover crops in the off-season or in crop rotation may be a strategy to improve the physical, chemical and biological characteristics of the soil and prevent erosion processes. Several grass and leguminous species may be employed for such end. Each has a peculiar dynamic with regard to cover speed and persistence in the soil. The dynamics of cover rates and decomposition of cover crops and the effect of the species' root system on the soil's physical features are analyzed. Assay design was totally randomized, with eleven treatments and four replications, with cover crop species Brachiaria brizantha Hochst. (Stapf), Crotalaria bleviflora, Crotalaria juncea, Crotalaria ochroleuca, Stylosanthes capitata + Stylosanthes macrocephala, Canavalia ensiformis, Cajanus cajan cv. IAC/Fava-larga, Cajanus cajan cv. IAPAR 43, Pennisetum glaucum, Mucuna cinereum and Mucuna aterrima. Soil cover rates were evaluated at 20, 40, 60 and 80 days after seeding. Decomposition rates of vegetal wastes were analyzed at 15-day regular intervals as from the cutting of the crop. Canavalia ensiformis, Mucuna cinereum and Mucuna aterrima covered the soil totally after eighty days of seeding and Pennisetum glaucum had the greatest resistance after sixty days from cutting. [ABSTRACT FROM AUTHOR]

Climate change brings a huge threat to the sustainability of food production and other livelihood activities in vulnerable areas like Nigeria, because it relies majorly on rain-fed agriculture. This study aimed to evaluate the effect of climate smart agricultural practices (CSAP) on food security of farming households in the Kwara State, North-Central Nigeria. A three-stage sampling technique was used to select ninety farming households, and a structured questionnaire to obtain information for the study. The collected data were analyzed using the food security index, adaptation strategy use index and logistic regression model. The result revealed that crop rotation is the most used CSAP in the study area, and that 16.67 % of the respondents are low users, 53.33 % medium users and 30 % high users of CSAP. It was also observed that 58.9 % of the farming households are food secured, while 41.1 % are food insecure. The logistic regression showed that the food security of the farming households is significantly affected by education, access to extension visits, farm size, off-farm income and CSAP.

Cover crops (CC) and crop rotation are key components of a sustainable crop production system. The objectives of this study were to (i) evaluate the effect of winter CC on nitrogen (N) supply to the subsequent maize crop, and to (ii) evaluate the effect of CC on soil cover and weed population. Three winter CC were evaluated: black oat (BO) (Avena strigosa Schieb), white lupin (WL) (Lupinus albus), and oilseed radish (OR) (Raphanus sativus L.), as single species and in a mix. The three CC mixes included: BO+WL; BO+OR; and OR+WL. In addition to CC treatments a set of five N application rates (0, 60, 120, 180, and 240 kg N ha-1) were included on plots under winter fallow (WF). The winter CC supplied plant-available N to the subsequent maize crop varying from 25 to 53 kg N ha-1 with BO and WL, respectively. The mix of CC varied less in N supply (38-42 kg N ha-1). Soil cover and weed suppression varied between CC. The results suggest that BO can be used to attain rapid soil cover. Black oats also provided better soil cover after CC flattening, likely due to the higher C:N ratio and slower residue decomposition. The higher C:N ratio may result in some N immobilization and reduced plant available N to the maize crop. However, BO also showed great weed suppression. Mixing CC is an alternative to merge the benefits of the individual species, enhancing the overall ecosystem services provided by them.

Abstract: The objective of this work was to determine the duration of the effects of the mechanical interventions scarification and raised bed on soybean (Glycine max) grain yield on an Alfisol, as well as to evaluate, through physical indicators, if the use of cover plants during winter increases the duration of these effects. The experimental design was a complete randomized block with four replicates. Two factors were evaluated. The first consisted of types of soil preparation systems: SC14, scarification in November 2014; SC15, scarification in November 2015; RB14, raised bed built in November 2014; and RB15, raised bed built in November 2015. The second consisted of the type of cover crop used: winter fallow, oat, ryegrass, and wheat. From November 2015 to April 2016, soybean was cultivated under the different soil preparation systems. Soil density, total porosity, macroporosity, microporosity, soil saturated hydraulic conductivity, soil resistance to mechanical penetration, and soybean grain yield were evaluated. There was no effect of cover plants after one crop season on the maintenance of soil physical attributes. Changes in soil density, total porosity, and resistance to mechanical penetration, promoted by scarification, are noticeable up to at least 18 months. The continuance of these modifications reflects in soybean grain yield in the second harvest.

Abstract: The objective of this work was to evaluate the effect of raised seedbeds associated with irrigation on the yield of soybean (Glycine max) rotated with rice (Oryza sativa) in lowland conditions in Southern Brazil. Field experiments were conducted in two crop seasons (2014/2015 and 2015/2016), with two planting systems (raised seedbed and flat planting) and two irrigation managements (irrigated and nonirrigated). Water use, biological nitrogen fixation, and yield were evaluated. The water used for raised seedbeds was 14% (151 m3 ha-1) and 27% (163 m3 ha-1) lower than that for flat planting in the first and second crop seasons, respectively. Irrigation increased nodule number per plant, nodule dry weight, and biological nitrogen fixation. The average grain yield of the raised seedbed system was 10% (529 kg ha-1) and 9% (362 kg ha-1) higher than that of flat planting in 2014/2015 and 2015/2016, respectively. Irrigation improved yield by 5% (203 kg ha-1) and 7% (265 kg ha-1) in each crop year. The use of raised seedbeds associated with irrigation improves the yield of soybean grown in rotation with rice in lowland in Southern Brazil.

The aim of this work was to evaluate the development of Chia at different sowing times and plant spacings. The experiment was conducted in a commercial area located in the Northwest Region of RS in the municipality of Novo Machado. The experiment was conducted in a bifactorial arrangement with 2 spacings and 3 sowing times, with four replications. The factors analyzed were three different sowing times (January 15 and 30, and February 15) combined with two spacings (17 and 45 cm). The following parameters were evaluated: mean plant height, ear length, yield, weight of one thousand seeds, germination and first germination test count. The variable percentage of germination and its derivations were transformed into arcsin (X/100)1/2. The study showed that chia can be cultivated in the region, achieving good results for the parameters evaluated, mainly for grain yield. Sowing carried out in January and at the spacing of 17 cm between rows provided the best results.

ABSTRACT: The aim of this experiment was to identify grazing height targets for Alexandergrass pastures under continuous stocking in integrated crop-livestock system (ICLS). For this purpose, twelve pastures were cultivated into an ICLS area, and maintained at 10, 20, 30, or 40 cm using grazing goats. The following variables were analyzed: leaf and herbage mass, accumulation rate, and allowance; leaf:stem ratio; chemical composition of hand-plucked samples; stocking rate; average daily gain and gain per area. The data were submitted to regression and correlation analysis. Significance was set at 5% (P≤0.05). The main results were: i) herbage and leaf lamina mass increased linearly with grazing height, and pastures maintained at 20 cm already presented the minimum amount recommended for soil cover in ICLS; ii) animal performance achieved an upper asymptotic plateau in pastures maintained around 30-40 cm and it was highly correlated with both grazing height and forage availability (mass and allowance). Alexandergrass pastures under continuous stocking in ICLS should be maintained between 30-40 cm to improve both cover crop biomass and animal performance.

Abstract: The objective of this work was to evaluate the effect of winter cover crop species on the agronomic performance of soybean (Glycine max) cropped in succession, under a no-tillage system. The study was conducted during three crop seasons (2011/2012, 2012/2013, and 2013/2014), with the following cover crops: white oat (Avena sativa), black oat (Avena strigosa), ryegrass (Lolium multiflorum), vetch (Vicia sativa), forage radish (Raphanus sativus), the intercrop black oat + forage radish, and wheat (Triticum aestivum) as the standard management. Forage radish and the intercrop black oat + forage radish provided greater soil cover rates after 30 days of planting, as well as dry matter production in the three crop seasons. After 45 and 90 days from desiccation, however, white oat and ryegrass showed the highest soil cover rate. Black oat and the intercrop black oat + forage radish provided higher soybean yield than the standard management with wheat, in the 2012/2013 and 2013/2014 crop seasons. Winter cover crops can significantly affect soybean yield in succession, and black oat and the intercrop black oat + forage radish stand out for this purpose.

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This study aimed to evaluate the performance of goats grazing black oat (Avena strigosa) fed with different levels of supplementation as well as its influence on soil resistance to penetration and corn yield grown in succession with increasing levels of N top dressing. In the winter, ten month‑old Boer goats received supplementation levels at 0, 5, 10, and 15 g kg-1 of body weight, in continuous stocking grazing, with variable stocking rate, and with a control without grazing. In the summer, the main plots were divided into sub-plots and N was applied at increasing levels in top dressing on the corn crop (0, 50, 100, and 150 kg ha-1 of N as urea). In the winter, the forage sward mass and its forage production, stocking rate, animal live weight gain and soil resistance to penetration were evaluated. In the summer, the corn yield components were evaluated. Stocking rate increased as supplement levels increased, which also increased the intensity of trampling and hence the resistance to soil penetration in the surface layer without affecting the grain yield of the corn grown in succession. When winter grazing is in accordance with the forage height and the fertilization, it reduces the need for nitrogen in the summer to obtain the corn yield produced in ungrazed areas in the winter.

In order to meet the great need to increase agricultural yield associated with the research of healthy products, which do not cause problems for the environment, this study aims to investigate the influence of mass quantity on black oats, radish and hairy deer in the emergence and development of B. pilosa, S. rhombifolia and G. max. It was carried out in the greenhouse with 10, 20, 30, 40 or 50 g of the studied weights. The weed and soybean seeds were sown and evaluated for 10 days to record their emergence. For the initial development of plants, five seedlings were transplanted, which evaluation occurred after 30 days. In general, increasing the amount of weight also increased the percentage inhibition of the weeds studied, but did not negatively influence the soybean. ESI (Emergence Speed Index) and ES (emergence speed) were negatively affected by the increase in weight, with the exception of soy ES. Weed mass was negatively influenced by cover crops, but did not cause problems for soybeans. Thus, the greatest amount of mass in relation to the winter cover crops studied was lower, being the infestation of these weeds without significant problems for the soybean. Finally, species may be recommended for further field studies as cover crops in large areas in the no-tillage system.

Abstract: The objective of this work was to evaluate watermelon (Citrullus lanatus) cultivation in regeneration areas of a sugarcane field, under different soil management systems and N fertilization regimes. Two experiments were carried out in the 2014/2015 and 2015/2016 harvest seasons, in areas of sugarcane plantation in Andradina, in the state of São Paulo, Brazil. Cultivations were performed in a randomized complete block design, with plots and subplots, and four replicates. The plots represented the tillage systems (conventional, minimum tillage, and no-tillage), and the subplots, the different N fertilization rates (0, 100, 200, and 300 kg ha-1) applied as topdressing. In 2014/2015, the minimum tillage system resulted in the highest commercial yield of 70.2 Mg ha-1. In 2015/2016, there were no differences for yield among tillage systems; however, yield differed among N treatments. The highest commercial yields of 64.1 and 31.1 Mg ha-1 were achieved with the N doses of 253 and 209 kg ha-1 as topdressing, respectively, in 2014/2015 and 2015/2016. Watermelon can be cultivated in regeneration areas of sugarcane field, and the demand of N by the plant does not depend on the soil tillage system.

As world demand for soybeans increases, it is necessary to use alternative techniques to increase the production of the crop in a sustainable way. Biological nitrogen fixation - BNF performed by diazotrophic bacteria is considered an efficient and economical source for N supply to the soybean. This study aimed to evaluate soybean productivity and soil bioindicators as a function of the inoculation of Bradyrhizobium japonicum isolated and the co-inoculation with Azospirillum brasilense in succession of autumn-winter crops. The experiment was carried out in the experimental area of Embrapa Western Agriculture, in Dourados, MS, in the 2016/2017 harvest season. The experimental design was in randomized blocks in subdivided plots with three replicates. In the plots were allocated the four autumn-winter crops (single corn, corn intercropped with Brachiaria ruziziensis, single cowpea and single B. ruziziensis), and in the subplots inoculation via seeds: without inoculation (control); inoculation with B. japonicum and coinoculation of B. japonicum + A. brasilense. No significant effect of inoculation methods was observed on the studied variables as well as an interaction of inoculation vs. autumn-winter crops. The autumn-winter crops influence the grain yield, which the soybeans cultivated in succession to intercropping maize and cowpea achieved better averages. The microbial biomass carbon, metabolic and microbial quotients were influenced by the crops, being the highest value of microbial biomass carbon found in succession to intercropped corn, in relation to cowpea, B. ruziziensis and single maize. The activity of the acid phosphatase enzyme was not influenced by any factor studied. The use of autumn-winter crops contributes to the performance of soybeans in succession and contribute to the increase of soil microbial biomass. [ABSTRACT FROM AUTHOR]

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Cassava cultivation is conducted primarily in conventional soil tillage systems, and due to the slow development at the initial stage aggravates erosion problems and can render the crop unsustainable in many regions. One of the alternatives is to improve the soil cover through the consortium or crop rotation with legumes for green manure. The objective of this work is to evaluate the cultivation of cassava in the conventional cultivation system and in a consortium with species of green manure, under the edaphoclimatic conditions of the North End of Tocantins. The experiment was implemented in a randomized block design, with five replicates. Five treatments were tested: cassava in monoculture and without fertilization; cassava in monoculture and conventional system; manioc intercropped with Canavalia ensiformis; Cajanus cajan and Crotalaria juncea. The legume that presents the greatest increase of phytomass is the bean of pork covering completely between the lines of planting, demonstrating potential of control to the erosion. The results allowed to conclude that the cultivation in a conventional system was superior in relation to the morphological performances and yield of cassava. The consortium showed feasibility in relation to the best use of the area, control of weeds, soil conservation and mainly increase of organic matter in the soil. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the effect of different winter cover plants on soil physical and chemical attributes and corn crop productivity. The experiment was carried out for three crops, from 2011 to 2014. The treatments were winter cover crops vetch, black oat, blue lupin, wild radish, ryegrass and field pea cultivated alone and intercropped with black oat + vetch, black oat + wild radish + vetch, black oat + wild radish, and a control treatment, without the use of cover crops (fallow). The experimental design consisted of random blocks with three repetitions. Chemical and physical soil parameters were evaluated, as well as yield of dry plant biomass of the cover crops and yield of corn cultivated in sucession. The greatest production of dry mass for field pea was obtained in the 2011/2012 crop and for the treatments with black oat + vetch and black oat + wild radish + vetch, in 2012/2013 and 2013/2014. Corn grain yield was higher in the treatments utilizing Fabaceae species and intercropping in the 2011/2012 crop. In the 2012/2013 and 2013/2014 crops, the greatest yield of corn grains was found in the treatments with black oat + vetch + wild radish and blue lupin as cover crops. Growing cover crops for three consecutive years resulted in increase in the organic matter contents and availability of phosphorus and potassium in the soil. [ABSTRACT FROM AUTHOR]

The economic importance of practices of soil conservation, forests and several structural issues of agro-livestock establishments in the state of Minas Gerais, Brazil, was measured by employing spatial hedonic price method. Results confirm the importance of conservation practices with special reference to terraces that increase land price. The use of crop rotation had a negative relationship with land price. Inverse relationship between legal reserve areas and land price is underscored. The above may be interpreted as the cost of the opportunity of forest areas. [ABSTRACT FROM AUTHOR]

The influence of composted sewage sludge and nitrogen in nutrition factors and the development of sunflower crops after the sixth application in crop rotation are evaluated. The experiment was conducted on the Experimental Farm São Manuel, Faculty of Agronomic Sciences of UNESP in Botucatu SP Brazil. Experimental design comprised randomized blocks with 6 treatments and 4 replications: T0 - without nitrogen fertilization; T1 - synthetic nitrogen fertilization; T2 - 50% nitrogen fertilization derived from sewage sludge and 50% in synthetic form; T3 - 100% nitrogen fertilization from sewage sludge; T4 - 150% nitrogen fertilization from sewage sludge; T5 - 200% nitrogen fertilization from sewage sludge. Composted sewage sludge increased N, P, S, Fe, Mn and Zn rates in leaves and a greater export of all nutrients. Chemical nitrogen fertilization decreased K and increased B, Fe and Mn in the leaf and an increase in the export of all nutrients. Composted sewage sludge and nitrogen fertilizer increased plants' height, stalk diameter, number of leaves and chapter diameter. [ABSTRACT FROM AUTHOR]

Abstract The objective of this work was to evaluate the long-term effects of the surface application of lime on soil fertility and on the mineral nutrition and grain yield of soybean, and of black oat and sorghum in crop succession. The experiment was carried out on a clayey Oxisol, in a randomized complete block design, with four replicates. Treatments consisted of lime the rates of 0, 1,000, 2,000, and 4,000 kg ha-1, applied in October 2002 and November 2004. Soil samples were collected at five soil layers, down to 0.60-m depth. Surface liming was effective in reducing soil acidity and increasing Ca2+ and Mg2+ contents in the subsurface. Moreover, it increased available phosphorus contents and soil organic matter in the long term (48 to 60 months after the last lime application). Surface liming improved plant nutrition, mainly for N, Ca, and Mg, and increased dry matter production and grain yield of the crops, even in years with regular distribution of rainfall. The greatest productivities of soybean, black oat, and sorghum were obtained with the respective estimated lime doses of 4,000, 2,333, and 3,281 kg ha-1, for shoot dry matter, and of 2,550, 3,555, and over 4,000 kg ha-1, for grain yield.

Abstract The objective of this work was to evaluate total soil carbon and nitrogen, as well as their contents in particulate and mineral-associated C fractions; to determine C stock and sequestration rates in the soil; and to verify the effect of C and N contents on soil aggregation, using different crop rotations and crop sequences under no-tillage. The study was carried out for nine years in a clayey Oxisol. The treatments consisted of different cropping systems formed by the combination of three summer crops (cropped until March) - corn (Zea mays) monocropping, soybean (Glycine max) monocropping, and soybean/corn rotation - and seven second crops (crop successions). Soil samples were taken at the 0.00-0.10-m layer for physical fractionation of C and N, and to determine soil aggregation by the wet method. Soybean monocropping increased C and N in particulate C fraction, while the crop systems with corn monocropping x pigeon pea (Cajanus cajan), corn monocropping x sun hemp (Crotalaria juncea), and soybean monocropping x corn as a crop succession increased total C in the soil. Greater rates of soil C sequestration were observed with soybean/corn rotation and with soybean monocropping, as well as with sun hemp as a second crop. The increase in total N increases soil C stock. Soil aggregation was most affected at particulate C fraction. Increases in soil N promote C addition to particulate fraction and enhance soil aggregation.

Abstract The objective of this work was to evaluate the physical quality of an Oxisol under no-tillage subjected to different crop rotations and crop sequences. The experiment was carried out in a clayey Oxisol, during six years, in a randomized complete block design, with strip plots and three replicates. The following physical indicators of soil quality were evaluated: soil density and carbon content, as well as mean weight diameter and tensile strength of aggregates. Treatments consisted of three summer crop rotations - corn/corn (Zea mays), soybean/soybean (Glycine max), and soybean/corn - and of seven second crops (crop sequences) - corn, sunflower (Helianthus annuus), oilseed radish (Raphanus sativus), pearl millet (Pennisetum americanum), pigeon pea (Cajanus cajan), grain sorghum (Sorghum bicolor), and sun hemp (Crotalaria juncea). Crop rotations and sequences did not affect soil carbon contents. Corn, as a summer crop, increased the tensile strength and mean weight diameter of aggregates, similarly to pearl millet and sorghum as second crops. Soybean/corn rotation with sun hemp as a second crop increases soil physical quality, promoting higher tensile strengths and lower soil densities.

This study aimed to evaluate the influence of different cultures second crop on the population of the nematode P. brachyurus, and the soybean crop productivity. The experiment was conducted at Embrapaagrosilvopastoral during agricultural year 2012/13, 2013/2014 and 2014/15, 0.4 ha of tracks. During the 2012/2013 crop soybeans planted in every area, in the off-season in 2013, two corn cultivars, two soybean and corn consortium with B. ruziziensis in 2013/14 crop was sown soybeans again in the off-season 2014 They were sown three soybean cultivars, a cultivar of corn and intercropping of millet with C. ochroleuca. In the season 2014/15 soybean was sown in every area and in the off-season 2 cultivars of maize and 3 soybean cultivars. Productivity was determined and the population of the P. brachyurus in roots. It was observed that millet consortium and C. ochroleuca were efficient in controlling the nematode. There were differences of reactions not only among species but within species and between the genotypes and soybeans, interfering with the population of the P. brachyurus. In the season 2013/2014 the soybean yield was influenced by the treatments, but the harvest 2014/2015 there was no statistical difference.

ABSTRACT Several authors have been questioned the desiccation interval between the coverage plants and sowing plants for the soybean crop. Therefore, this study aimed to evaluate the desiccation time of the spring sorghum as a predecessor crop for summer soybean and then for autumn bean, focusing on the straw formation for maintenance of the no-tillage system and to evaluate the yield of soybeans and beans grain, as well as analyzing the interference of sorghum straw in these cultures. The experiment was developed in the Teaching and Research Farm of FE/UNESP located in Ilha Solteira/SP where it was used an experimental design of randomized blocks with five treatments and six repetitions. The treatments consisted of five different intervals between sorghum desiccation and soybean sowing (being with D7 - Drying sorghum seven days before the soybean sowing; and successively for D14, D21, D28 and D35). In order to analyze the results, it was used the Tukey test for a 10% level of significance and the statistical program called Sisvar. The "Cober Crop" sorghum exerted influence on soybean yield but this effect was not lasting for the bean crop in succession to the soybeans.

ABSTRACT The increase in the area planted with Crotalaria spectabilishas occurred by several factors, highlighting the potential to reduce the nematodes, nitrogen fixation and the high production of biomass. By becoming a species sown as a crop, it is necessary to control the weeds that coexist with showy crotalaria. This change in the use of this crop creates the possibility of this specie becoming a weed. The aim of this study was to assess the potential use of herbicides applied in preemergence and postemergence of C.spectabilisfor different purposes (control of volunteer and selectivity plants). Three experiments were installed in a greenhouse (two with herbicides applied in preemergence - in soils with distinct textural categories; and one experiment with herbicides applied in postemergence). The results of the experiments with herbicides applied in preemergence showed that: amicarbazone, atrazine, diuron, metribuzin, prometryn, fomesafen and sulfentrazone showed effectiveness for control of C.spectabilis in clayey soil. Besides these, flumioxazin and isoxaflutole also showed potential to be used in the control of showy crotalaria in soils with loam texture. In relation to the postemergence herbicides, atrazine, diuron, prometryn, flumioxazin, fomesafen, lactofen, saflufenacil, amonio-glufosinate and glyphosate can be used aiming the chemical control of C.spectabilis. Herbicides chlorimuron-ethyl, diclosulan, imazethapyr, pyrithiobac-sodium, trifloxysulfuron-sodium, clomazone, pendimethalin, S-metolachlor and trifluralin applied in preemergence, and imazethapyr, pyrithiobac-sodium, flumiclorac, bentazon and clethodim applied in postemergence caused low levels of injury to C.spectabilis plants, making necessary the development of new searches to ensure the selectivity of these products.

Cover crops are important for improving soil quality. However, soil properties usually have some spatial dependence. Thus, this study aimed to evaluate the effect of winter cover crops on physical properties of soil and soybean yields using thematic maps. Five winter treatments were used: black oats; intercropping 1 (forage turnips and black oats); intercropping 2 (forage turnips, black oats and common vetch); wheat; and control. Macroporosity, microporosity, total porosity, bulk density and water content of the soil from 0 - 0.1 m depths were evaluated after the winter cover crop management. Soybeans were sown over the entire area in the summer after the winter cover crop management, and the soybean yield was determined for each treatment. Maps for each treatment were created and compared to the control treatment using the relative deviation coefficient (RDC). The cover crops improved the total macroporosity of the soil in some regions of the study area. The black oats were more efficient at maintaining higher water content of the soil, and it can be used to decrease the bulk density.

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Soil management, featuring techniques that make possible great sustainability, aims at soil recuperation and sustainability, greater productivity and greater economic gain to the producer. Soil fertility (phosphorus, potassium, organic matter, pH) is evaluated with regard to depth of samples and soil and crop preparation systems. Experiment was undertaken in Red-Yellow Latisol and a sub-subdivided split scheme was adopted. Soil preparations comprised (1) PRT - traditional preparation (plowing grid and two level grids); (2) PRA - alternative preparation (subsoil); (3) PDA - zero tillage with alternative preparation every four years; (4) PDC - continuous zero tillage. Crop sequence was the second factor employed, namely: (1) SF: soybean - beans; (2) MF: corn - bean; (3) SM: soybean - corn; 4) MM: corn - corn. PRT and PDC presented lower fertility rate at the soil surface layer. PRT presented less amounts of phosphorus, potassium and organic matter; pH had lower rates in PDC and PRT. [ABSTRACT FROM AUTHOR]

Some plant species can change soil phosphorus (P) availability and this may be an important tool in managing tropical high fixing phosphorus soils. An experiment was conducted to evaluate phosphorus transformations in the soil and phosphatase activity during periods of Congo grass (Brachiaria ruziziensis, Germain et Evrard) growth in two tropical soils receiving 20, 40, 80, 160 mg dm-3 of inorganic P. Plants were grown for 84 days in 8-L pots. Acid phosphatase activity, P in the microbial mass, soil organic and inorganic P and P accumulation by Congo grass were evaluated. Phosphorus fertilization increased soil P availability, Congo grass yields and P accumulation in the plant. On average, less labile P forms in the soil were not changed by Congo grass; however, the P in the soil extracted with HCl (P-Ca - non labil form) decreased. This decrease may have resulted from the combination of the presence of grass and phosphatase capacity to dissolve less available P in the soil. Thus, soil exploration by Congo grass roots and the subsequent extraction of calcium phosphate may have increased the P concentration in the plant tissue. Despite the decrease in the P extracted from the soil with HCl resulting in increased labile P forms in the soil, the effect of Congo grass on the availability of P depends on the soil type.

The evaluation of technologies employed at the agricultural production system such as crop rotation and soil preparation, both associated with crop-livestock integration, is crucial. Therefore, the aim of the present study was to evaluate the incorporation of lime for three no-tillage systems and cultural managements in system of crop-livestock integration, with emphasis on corn grain yield. The experiment was conducted from January 2003 to April 2005 at Selvíria city, MS, in Dystroferric Red Latosol, clay texture. The experimental design was randomized blocks with split plots consisted of three main treatments, aimed the soil physics conditioning and the incorporation of lime: PD - No-no-tillage; CM - minimum no-tillage, and PC - conventional no-tillage; and of two secondary treatments related to the management: rotation and crop succession, with four replications. Data on agronomic traits of maize were analyzed: plant height, stem diameter, height of the first spike insertion, 100 grains weight and grain yield. The results showed that the maize produced under the system of crop-livestock integration is quite feasible, showing that grain yields are comparable to averages in the region and the different soil physical conditioning and incorporation of lime did not influence the corn yield as well as the cultural managements, rotation and succession, did not affect the maize crop behavior after two years of cultivation.

The objective of this study was to evaluate the growing of soil improving crops on the population of Rotylenchulus reniformis in naturally infested soil. It was evaluated the effect of 6 species of plants as cover crops in winter and 13 summer species and a fallow treatment on the nematode population under greenhouse. After 60 days, the root system was collected. Then, a sample of soil was taken in order to extract juveniles from the soil and quantification the final population of the pathogen in each pot for determining of the reproduction factor (RF). Fallow and all winter species of green manure, except hairy vetch, reduced the population of R. reniformis after cultivation in infested soil, in comparison to the control. Regarding summer cover crops, it was observed that sorghum ‘SI03204’ (Sorghum vulgare), millet ‘BRS1501’ (Pennisetum glaucum), Brachiaria ruziziensis, finger millet (Eleusine coracana), estylo ‘Campo Grande’ (Stylosanthes capitata x S. macrocephala), peanut ‘IAC Tatu ST’ (Arachis hypogaea) and dwarf velvet bean (Mucuna deeringiana) reduced the population of R. reniformis, when compared to the control, could be used in the management of this nematode.

The west of São Paulo is characterized by the recent expansion of sugarcane, occupying pasture lands and cereal crops. This region is characterized by sandy soils, high evapotranspirative demand and periods of water deficit during the rainy season. This work was developed at the "Polo Regional do Extremo Oeste" in Andradina, SP, Brazil the objective of evaluating the yield crop combined with different soil management systems, in areas of sugarcane renewal. The split plot design was employed, was installed in a 3X6 consisting of soil tillage treatments (conventional, low-tillage and no-tillage) and 5 species used in succession, being an association of Crotalaria juncea L. and Dolichos lablab L .; peanuts, soybeans, corn, sorghum, and fallow. Was analyzed dry shoot dry mass and yield components of crop rotation. As a result it observed the low yield of succession cultures due to the water deficit in the vegetative and reproductive growth phase. [ABSTRACT FROM AUTHOR]

O objetivo deste trabalho foi determinar os efeitos de sistemas de manejo do solo sobre os estoques e as frações de carbono orgânico de um Latossolo Amarelo, no cerrado do Piauí. Foram avaliados os sistemas: plantio convencional por três anos; plantio direto por três e cinco anos, com uso de milheto como cultivo de cobertura; e plantio direto por nove anos, dos quais sete com uso de milheto e dois com forrageira (Urochloa brizantha). Utilizou-se área de cerrado nativo como referência. Amostras de solo foram coletadas nos períodos chuvoso e seco, das camadas de 0,00-0,05, 0,05-0,10, 0,10-0,20 e 0,20-0,40 m, para determinação de: estoques e totais de carbono orgânico e nitrogênio; teores de substâncias húmicas; e índice de humificação. Na camada de 0,00-0,05 m, em ambos os períodos, foram observados os maiores teores de carbono no solo sob cerrado. No entanto, nos dois períodos e nas quatro profundidades, verificaram-se os maiores estoques de carbono e nitrogênio bem como os maiores teores de substâncias húmicas nos solos sob plantio direto por cinco e nove anos. Os maiores índices de humificação também foram observados nesses solos, no período seco. O plantio direto, associado ao uso de cultivos de cobertura, diminui a mineralização da matéria orgânica do solo, estoca carbono no solo em profundidade e favorece o sequestro de carbono em áreas do cerrado do Piauí.The objective of this work was to determine the effects of soil management systems on the stocks and fractions of organic carbon of an Oxisol (Xantic Ferralsol), in the cerrado of the state of Piauí, Brazil. The following systems were evaluated: a three‑year‑old conventional tillage; a three‑ and a five‑year‑old no‑tillage system, using millet as cover crop; and a nine‑year‑old no‑tillage, using millet as cover crop for seven and forage (Urochloa brizantha) for two years. A native cerrado area was used as a reference. Soil samples were collected in the wet and dry seasons from 0.00-0.05, 0.05-0.10, 0.10-0.20, and 0.20-0.40 m depths for determining: total organic carbon and nitrogen contents and stocks; humic substances content; and humification index. The highest carbon contents were observed in the soil under cerrado, at 0.00-0.05 m depth, in both seasons. However, the highest stocks of carbon and nitrogen as well as the highest contents of humic substances were verified in the soil with no‑tillage system for five and nine years, in both seasons, at all evaluated depths. The highest humification index was also observed in these soils, in the dry season. No‑tillage associated with cover crops decreases soil organic matter mineralization, increases soil carbon stocks in depth, and favors carbon sequestration in cerrado areas of Piauí state.

As podridões da base do colmo (PBC) e grãos ardidos (GA) ocorrem em lavouras de milho, causando prejuízos aos produtores e contaminando os grãos com micotoxinas. O objetivo deste estudo foi quantificar os efeitos do monocultivo de milho, da rotação de culturas com feijoeiro e da adubação nitrogenada na incidência de PBC e GA, nos teores de fumonisinas, peso de mil sementes (PMS) e no rendimento de grãos de milho. O delineamento experimental adotado foi em blocos casualizados com parcelas subdivididas e quatro repetições por tratamento. Na parcela principal, foram testados três híbridos de milho: P30F36, AS 1575 e Maximus. Nas subparcelas, foi avaliada a resposta dos híbridos a cinco doses de nitrogênio (N), equivalentes a 0; 75; 140; 215 e 290kg de N ha-1, em ambos os sistemas de cultivo. Não foram observadas diferenças significativas para os valores médios de PBC, fumonisina e rendimento de grãos nos dois sistemas de cultivo avaliados. Para os valores médios de GA e PMS, ocorreram diferenças entre híbridos somente quando cultivados em rotação de cultura. A incidência dos parâmetros PBC e GA, quando em monocultura, foi superior aos encontrados quando cultivado em rotação de culturas. As variações médias do PMS e rendimento de grãos foram superiores quando em rotação, comparativamente ao sistema de cultivo em monocultura. As diferentes doses de N explicaram apenas parcialmente as variações observadas em todas as variáveis analisadas.The stalk rot (SR) and grain rot (GR) occur in crops as corn, causing losses to farmers and contaminating the grain with mycotoxins. The aim of this study was to quantify the effects of corn monoculture, crop rotation with common bean, and nitrogen fertilization on the incidence of SR, GR, fumonisin levels, weight of thousand seeds (WTS) and grain yield. The experiment was randomized blocks with split plot and four replicates per treatment. In the main plot were tested three maize hybrids: P30F36, AS 1575 and Maximus. In the sub-plots, each of the hybrids was evaluated in five levels of nitrogen (N), equivalent to 0; 75; 140; 215 and 290kg of N ha-1 in both cropping systems. There were no significant differences for mean values of SR, Fumonisin and grain yield in both cropping systems evaluated. For GR and WTS average values had differences between hybrids only when corn was grown in crop rotation with common bean. The annual growth rate of SR and GR parameters in corn monoculture ranged from 44.8 to 172.4 %, above the rate found on corn when grown in crop rotation. In turn, mean changes of WTS and grain yield was 1.2 to 17.6 % higher when in rotation compared to monoculture cropping system. The differences found in nitrogen rates partly explained the changes observed in all variables.

Com o objetivo de identificar as comunidades de plantas daninhas que ocorreram após o cultivo de milho em plantio direto na savana amazônica, foi realizado um levantamento fitossociológico em um experimento de manejo do solo. As coletas de identificação e quantificação das plantas daninhas foram realizadas quatro meses após a colheita do milho, durante os meses de junho e julho de 2010. As plantas foram avaliadas quanto a: classe botânica, família, espécie, número de indivíduos, frequência, densidade, abundância, frequência relativa, densidade relativa, abundância relativa, índice de valor de importância, método de propagação e ciclo de vida. A vegetação emergente na área de estudo foi de 419 espécies, das quais nove foram identificadas como da classe botânica das dicotiledôneas e seis das monocotiledôneas. As espécies da família Ciperaceae foram as mais abundantes, enquanto as famílias Poaceae, Ciperaceae, Asteraceae, Malvaceae e Fabaceae foram as que registraram os maiores números de indivíduos e frequências de espécies nas parcelas. Foi encontrada apenas a espécie Cordia curassavica com hábito de crescimento arbustivo. A espécie Cyperus rotundus apresentou os maiores valores em todos os parâmetros fitossociológicos avaliados, destacando-se o índice de valor de importância, que foi 1,5 vez maior que o de Brachiaria humidicola, o qual foi o segundo maior valor (40,49).The aim of this work was to identify the occurrence of weeds after five years of no-tillage corn cultivation in the Amazonian savannah. A phytosociological survey was conducted involving collection, identification, and quantification of the weeds, after corn harvest during June and July, 2010. The investigated properties included botanical classes, families, species, number of individuals, frequency, density, abundance, relative frequency, relative density, relative abundance, importance value index, propagation method, and life cycle. The emergent vegetation in the study area had 419species, nine of which were identified as Dicotyledons, while six were identified as Monocotyledons. Species in the Ciperaceae family were the most abundant, while the families Poaceae, Ciperaceae, Asteraceae, Malvaceae, and Fabaceae exhibited the highest number of individuals and species frequency per plot. Only the Cordia curassavica shrubby growth habit was identified. Cyperus rotundus species showed the highest values in all the phytosociological parameters evaluated, with an importance index value 1.5 times higher than that of Brachiaria humidicola which had the second highest value (40.49).

The aim of this study was to evaluate dry matter production of cover crops (oats, turnip, vetch and spontaneous plants) and their effect on bean yield and physical properties of soil after succession. The experimental design was randomized blocks, and treatments consisted of four species of cover crops: oat, turnip, vetch and spontaneous plants, with five replications. The cover crops were sown in winter; when in full bloom, they were cut close to the ground and left underground. The bean crop was then sown underneath this residue in a no-till system. The results show that the cover crop that yielded the most dry matter was oats with 4,900 kg ha-1, which did not differ statistically from turnip with a yield of 4,000 kg ha-1. The spontaneous plants produced the least amount of dry matter and differed from the other treatments. The development of vetch was hampered by the environmental conditions of Marechal Cândido Rondon, State of Paraná, with dry matter yield of 2,375 kg ha-1. The highest bean yield (1,204 kg ha-1) was found for the planting carried out in succession to oat, and the lowest after succession of vetch (697 kg ha-1) and spontaneous plants (575 kg ha-1). Cover crops had no effect on macroporosity and total porosity of soil depth from 0.05 to 0.20 m. There was a statistical difference in soil bulk density in the layer from 0.05 to 0.10 m, and bulk density (1.18 kg dm-3) was obtained in the treatment where the bean crop was cultivated after spontaneous plants.

Uma alternativa para suprir o aporte anual de palha exigido para manutenção do sistema plantio direto (SPD), nas regiões tropicais, é o cultivo de milho consorciado com urochloas. Com o objetivo de identificar o melhor sistema de cultivo de duas espécies forrageiras (Urochloa brizantha e Urochloa ruzizienses) em consórcio com o milho (Zea mays L.) em sistema plantio direto, foi realizada a presente pesquisa. O milho foi semeado em consórcio com as forrageiras em cinco sistemas de cultivo. Foi utilizado o delineamento em blocos ao acaso, em esquema fatorial (2x4+1), com quatro repetições. Foram avaliadas: massa seca de palha do milho, massa seca da palha de urochloa, massa seca total de palha, população de plantas de milho, massa de 1000 grãos e produtividade de grãos. Os resultados demonstraram que o consórcio de milho com urochloa não apresentou efeito negativo na produtividade do milho e incrementou o aporte de matéria seca no sistema de produção sob plantio direto. A escolha de determinado sistema de cultivo depende do gerenciamento e da disponibilidade de máquinas, visto que todos os sistemas apresentaram comportamento positivo em relação à produtividade de grãos e à produção de palhada.An alternative to supply the annual input of straw required to maintain the no-tillage system (SPD) in the tropics is the cultivation of maize intercropped with Urochloa. In order to identify the best cropping system of two forage species (Urochloa brizantha and Urochloa ruzizienses) intercropped with maize (Zea mays L.) in no tillage system, the present study was conducted. Maize was seeded intercropped with forage in five cropping systems. The experimental design was in randomized blocks in factorial scheme (2x4+1) with four replications. There were evaluated: dry mass of maize straw, dry mass of urochloa straw, total dry mass of straw, maize plant population, mass of 1000 grain and grain yield. The results showed that maize intercropped with urochloa had no negative effect on grain yield and increased the input of dry matter in the production system under no-tillage system. The choice of a particular cropping system depends on the management and availability of machines, since all systems showed positive behavior in respect of grain yield and straw production.

Studies related to weed dynamics are essential for agricultural sustainability in tropical soils, as their interference can cause significant yield losses, especially in crops with lower competitive ability. This study aimed to assess the composition of weed communities in the third cropping season in areas submitted to distinct wintercroppings for two consecutive years. Evaluations were made in terms of species composition, level of infestation, and severity of occurrence of each weed species in relation to the others within the same area. The wintercropping management systems were: (1) Brachiaria ruziziensis; (2) corn intercropped with B. ruziziensis; (3) corn and (4) cowpea. Plant communities under these wintercrop systems were evaluated in the third year in terms of relative frequency, relative dominance, relative abundance and importance index for each species. Areas were also compared in terms of species composition by the Sorensen's similarity coefficient. Two years of distinct wintercrop managements were not enough to cause a significant shift in terms of weed composition and severity in a given area. There is also evidence that some weed species are more favored by specific crops, although the causes of this selective behavior are not fully explored in this article. The presence of B. ruziziensis, either alone or intercropped with corn, resulted in lower similarity coefficients when compared to areas where this species was not present. It is suggested that several mechanisms briefly discussed may be involved in the impact of the presence of B. ruziziensis on the weed community.Estudos relacionados à dinâmica de plantas daninhas são essenciais paraa sustentabilidade da agricultura em solos tropicais, uma vez que a interferência pode causar perdas significativas na produção, especialmente em culturas com baixa capacidade competitiva. Objetivou-se com este estudo avaliar a comunidade infestante em áreas submetidas a distintos manejos de inverno nos dois anos anteriores, em termos de composição da flora infestante, do nível de infestação e da severidade da ocorrência de cada espécie daninha, em relação às demais, na mesma área. Os manejos de inverno avaliados foram: (1) Brachiaria ruziziensis, (2) milho em consórcio com B. ruziziensis, (3) milho e (4) feijão-caupi. As comunidades de plantas daninhas nesses sistemas de manejo foram avaliadas em termos de frequência relativa, abundância relativa e dominância relativa, e o índice de valor de importância foi calculado para cada espécie em cada área estudada. As áreas também foram comparadas em termos de composição de espécies, pelo coeficiente de similaridade de S0rensen. Dois anos de manejo distinto na área não são suficientes para ocasionar alterações significativas em termos de composição e severidade de espécies em uma dada área. Há evidência de que algumas espécies daninhas são mais favorecidas pela presença de determinada cultura, embora as causas dessa seleção não sejam completamente exploradas neste artigo. A presença de B. ruziziensis, tanto solteira como consorciada com milho, resultou em menor coeficiente de similaridade quando em comparação com áreas onde essa espécie não estava presente. Sugere-se que vários mecanismos sucintamente discutidos estejam envolvidos no impacto da presença de B. ruziziensis sobre a comunidade infestante.

O sistema de semeadura direta e os diferentes sistemas de produção nele adotados podem contribuir para a supressão de plantas infestantes. Em razão disso, o objetivo do presente trabalho foi avaliar o controle de plantas daninhas em função de diferentes sistemas de produção de grãos. Os tratamentos utilizados foram: I. Sistema "safra-pousio" - soja/ pousio/milho/pousio/arroz/pousio/soja; II. Sistema "safra-adubo verde" - soja/milheto/ milho/guandu/arroz/crotalária/soja; III. Sistema "safra-safrinha" - soja/aveia-branca/milho/ feijão-da-seca/arroz/mamona/soja; IV. Sistema "safra - forrageira"- soja + braquiária/milho + braquiária/arroz + braquiária/soja. Em novembro de 2009 (após três safras agrícolas), foi realizado o levantamento de plantas daninhas infestantes. Para isso, foi utilizado um quadro (0,3 x 0,3 m), lançado aleatoriamente quatro vezes dentro de cada parcela. As plantas foram identificadas, bem como feita a determinação do número total das espécies invasoras, da massa seca e da porcentagem de controle das espécies de acordo com o sistema de produção. Foi realizada ainda a análise fitossociológica da comunidade de plantas daninhas infestantes. Os sistemas safra-adubo verde, safra-safrinha e safra-forrageira apresentaram bom controle de plantas infestantes quando comparados ao sistema safra-pousio. Portanto, a presença de algum tipo de cobertura é importante para manter as características do solo favorável e um bom controle de plantas invasoras.Tillage and other agricultural production systems can contribute to weed suppression. Thus, the objective of this study was to evaluate weed control using different grain production systems. The treatments were: I. "Harvest-fallow" System- soybean/fallow/corn/fallow/rice/ fallow/soybean; II. "Harvest-green manure" System-soybean/millet/maize/pigeon pea/rice/ Crotalaria/soybean; III. "Harvest-out of season" System-soy/white oats/corn/dry bean/rice/castor oil/soybean; and IV "Harvest-fodder" System-brachiaria + soy/corn + brachiaria/brachiaria + rice/ soybeans.A weed survey was carried out in November 2009, after three growing seasons. A 0.3 x 0.3 m frame was randomly launched four times within each plot. The plants were identified, and the total number of weeds, dry weight, and control percentage of the species were determined according to the production system. The phytosociological analysis of the weed community was also conducted. The systems Harvest-green manure; Harvest-out of season and Harvest-fodder presented a good weed control when compared to the Harvest-fallow system. Therefore, the presence of some type of soil cover is important to maintain favorable soil characteristics and good weed control.