ABSTRACT Remote sensing has proven to be a promising tool allowing crop monitoring over large geographic areas. In addition, when combined with machine learning methods, the algorithms can be used for estimating crop yield. This study sought to estimate soybean yield through the enhanced vegetation index and normalized difference vegetation index. These vegetation indices were obtained using moderate-resolution imaging spectro-radiometer (MODIS) sensors on AQUA and TERRA satellites and multispectral instrument (MSI) sensor on Sentinel-2 satellite. Random forest (RF) algorithm was used to predict soybean yield and the estimation models were compared with the actual plot’s yield. The RF algorithm showed good performance to estimate soybean yield with our models (R2 = 0.60 and RMSE = 0.50 for MSI; R² = 0.63 and RMSE = 0.59 for MODIS). Vegetation indices with imaging dates corresponding to the crop’s maturation had a higher degree of importance in its predictive ability. However, when comparing the actual and predicted soybean production values, differences of 145 kg ha-1 in contrast to 4 kg ha-1 were found for the MODIS and MSI models, respectively. Therefore, the MSI sensor integrated with machine learning algorithms accurately estimated crop yields.

RESUMO O Sensoriamento Remoto orbital (SR) tem se mostrado uma ferramenta promissora, pois permite o monitoramento de culturas em grandes áreas geográficas. Além disso, quando métodos de Aprendizado de Máquina (AM) são combinados, os algoritmos podem ser usados para estimativas de produtividade de culturas. Assim, o estudo teve como objetivo estimar a produtividade da soja por meio dos índices de vegetação EVI (Enhanced vegetation index) e NDVI (Normalized Difference vegetation index), obtidos por meio dos sensores MODIS (Moderate-Resolution Imaging Spectroradiometer) dos satélites ACQUA e TERRA e MSI (Multispectral Instrument) do satélite orbital Sentinel-2. Neste estudo, o algoritmo Random Forest (RF) foi usado por ser amplamente difundido no estudos previsão de safras, e os modelos de estimativa de rendimento da soja foram comparados com o rendimento real da parcela. Os resultados mostraram bom desempenho do algoritmo de RF para estimar a produtividade da soja, obtendo R2 de 0,60 e RMSE de 0,50 para MSI; e R² de 0,63 e RMSE de 0,59 para MODIS na validação. Na modelagem, os índices de vegetação com datas de imagem correspondentes à maturação da cultura tiveram maior grau de importância na previsão. No entanto, ao comparar os valores reais e previstos de produção de soja, houve uma diferença de 145 kg ha-1 para o modelo gerado pelo MODIS e apenas 4 kg ha-1 para o MSI. Portanto, o sensor MSI integrado aos algoritmos de aprendizado de máquina estima com precisão o rendimento das culturas.

ABSTRACT Straw management associated with furrow opener mechanisms under a no-tillage system can enable better yields in the corn crop. Thus, this study aimed to evaluate corn productivity under a no-tillage system as a function of furrowing mechanisms and oat straw management. This research was conducted in the 2019/2020 growing season in Pato Branco, Paraná, Brazil, in a factorial scheme consisting of furrow opener mechanisms (shank and double disk) and oat straw management (rolled, desiccated, and crushed), with four replications. Oat dry matter, furrow depth, furrow width, tilled soil area, emergence rate index, initial and final plant stand, initial and final plant height, initial and final stem diameter, ear insertion height, number of rows per ear, number of grains per row, ear length, ear diameter, thousand-grain weight, and productivity were evaluated. The results were subjected to analysis of variance by the F-test at a significance 5% probability and the means were compared by Tukey’s test. Corn development, yield, and productivity were more influenced by the furrow opener mechanisms, standing out the use of a shank compared to the double disk.

ABSTRACT The importance of maintaining straw on the soil surface is a subject widely discussed and proven in the literature. However, the effects of this straw on planting efficiency and quality still lack information. In this sense, both time and method of the black oat management influence the permanence of the straw on the soil and, thus, can interfere in the next crop's germination and plantability of the seed drill. This study aimed to evaluate methods and times of black oat management and their implications on the plantability and development of the corn crop in succession in two harvests. A randomized block design with twelve treatments was used, consisting of the combination of three methods of management (crushed, rolled, and desiccated) and four times of management (0, 10, 20, and 30 days before the corn sowing) of black oat straw, arranged in a 3 x 4 factorial scheme, with four replications. The black oat management carried out 30 days before the corn sowing provides the highest corn emergence rate. Management methods that promote greater fragmentation of straw tend to offer less mechanical impediment to seedling development and result in a greater initial and final plant population.

ABSTRACT Onion production is conditioned to the adopted techniques during the cultivation. Sowing depth, soil preparation and cultivars are determinant factors for productivity to be increased. Two experiments were developed, the first with the objective of evaluating the effect of sowing depths and soil preparation methods on the germination and development of onion seedlings, while the objective of the second was to evaluate the productivity of onion cultivars as a soil preparation function. In experiment I, the split plot scheme was adopted, where the main plots consisted on soil tillage methods (total area and bed) and in the subplots, the sowing depths (0.5; 1.0; 1.5 and 2.0 cm), with six replicates. Experiment II was carried out in a split plot scheme, in which the main plots consisted on soil tillage methods (total area and bed) and in the subplots, such as onion cultivars (Itajubá, Rainha, Salto Grande, Ômega, Mulata and BR29), with four replicates. The 1.5 cm sowing depth provided greater speed of germination and plant stand. Raising beds offers the best initial seedling development. The onion cultivation under beds offers the highest vegetative development and productivity.

ABSTRACT This study aimed to evaluate the influence of management times and methods of black oat straw on corn crop development and yield under a no-tillage system for two crop seasons. A randomized block design was used with twelve treatments. They were arranged in a 3 x 4 factorial scheme with four replications, consisting of a combination between three methods (crushed, rolled, and desiccated) and four times (0, 10, 20, and 30 days before corn sowing). Black oat was evaluated for dry matter, while corn was for plant final population, height, stem diameter, ear insertion height, ear diameter, ear length, grain number per row, 1000-grain weight, and grain yield. All management methods and times interfered with corn crop yield components, but not all influenced final production. The method with the largest final corn population was not the same with an improved ear development. Such findings, however, may not be the same under highly favorable weather conditions.

ABSTRACT The effects of foliar application of Mo and use of N from cover crops (Crotalaria juncea L. and Canavalia ensiformis (L.) DC) on the performance of common beans were investigated in this study. Field experiments were carried out in a succession planting system (cover crops - common beans), and nitrate reductase activities were evaluated in the laboratory. The production of cover crops was done in a 2 x 4 factorial scheme installed in random blocks with four replications. The two cover crops sunn hemp and jack bean composed the first factor and the molibdenum doses (0, 40, 80, and 120 g ha-1) the second. These doses were applied as foliar fertilization using sodium molybdate (Na2MoO4) as Mo source. For bean cultivation, an unfertilized control treatment was evaluated.. Sunn hemp showed a linear positive response to Mo application in terms of shoot dry matter and N accumulation, while jack bean showed a quadratic negative response for shoot dry matter; for N accumulation, there was no adjustment of the regression models. Nitrate reductase activity in the common beans was up to three times higher at the Mo dose of 0 g ha-1 when compared to the treatments with Mo application to both cover crops. Cover crops or Mo doses had no significant effect on bean productivity.

ABSTRACT Ground Penetrating Radar (GPR) is a geophysical method that uses electromagnetic waves to study subsurface structure in different fields such as geology, agriculture and civil engineering. The wave penetration in the soil is strongly controlled by the electrical conductivity of soil components such as clay, organic matter, and water. In this study, tests were conducted in a floodplain in the Elizabeth Creek watershed (New Jersey – USA). We established one transect where measurements were completed using two techniques, common mid point (CMP) and constant offset profile (COP), both with 100- MHz frequency antennas. Measurements were also completed using 250 and 500 MHz shielded antennas. GPR showed good accuracy to study soil spatial variability and stratigraphy. Antennas of a higher frequency had less vertical investigation capacity and greater accuracy. In this study, it was not possible to clearly differentiate signals from organic matter and clay; this was the main limitation of the GPR system.

ABSTRACT Direct seeding systems are characterized by soil disturbance only occurring in the sowing line and the maintenance of the remaining area is achieved by covering with crop residues. Without total area soil mobilization as recommended by the no-tillage system, associated with the increase in the degree of soil compaction caused by the traffic of agricultural machinery, there can be a decrease in crop productivity. This study aimed to evaluate machine parameters, soil mobilization, and corn yield as a function of different furrow opener working depths (0.065, 0.095, 0.125, and 0.150 m) and evaluate the direct seeding of winter ground cover plants (black oat or forage turnip) in compacted Oxisol. The experiment was arranged in strips, in a randomized block design, with eight treatments and four replications. The deepening of the furrow opener shank increased the strength and power required at the drawbar in the seeding operation, as well as increased the soil mobilization in the seeding line. However, it did not prove to be an efficient management practice to increase corn productivity.

RESUMO. O intenso tráfego de máquinas no sistema plantio direto tem acarretado problemas de compactação do solo, ocasionando queda de rendimento das culturas. O objetivo deste trabalho foi avaliar a produtividade de soja em razão de mecanismos sulcadores e níveis de compactação do solo, em duas safras agrícolas. O experimento foi conduzido em Latossolo Vermelho distroférrico típico, em delineamento de blocos ao caso com parcelas subdivididas, onde nas parcelas foram dispostos os níveis de densidade (1,16; 1,20; 1,22 e 1,26 Mg m-3) e nas subparcelas os sulcadores (disco duplo e haste sulcadora). Foram avaliados a resistência à penetração, profundidade de sulco, área de solo mobilizada, estande final de plantas, altura de plantas, número médio de grãos por vagem, massa de 1.000 grãos, número de vagens por planta e produtividade da cultura. Independente do ano agrícola, a resistência à penetração aumentou com os níveis de compactação do solo até em torno de 0,20 m de profundidade. Na primeira safra, foi observado maior produtividade com o uso da haste. Na segunda safra, a haste proporcionou, aumento na profundidade de sulco, área mobilizada, altura de plantas e estande final de plantas, mas isso não se refletiu em ganhos de produtividade.

ABSTRACT. The heavy traffic of machines in no-tillage systems causes problems as soil compaction and loss of crops productivity. The objective of this paper is to evaluate the productivity of soybeans in reference to furrow openers and the levels of soil compaction in two crops. The experiment was conducted on Rhodic Hapludox by tracing random blocks with subdivided parcels. The soil bulk density levels were laid out in the parcels (1.16, 1.20, 1.22, and 1.26 Mg m-3) and the furrowers in the sub-parcels (double disc and shanks). The resistance to penetration, depth of the furrow, mobilized soil area, final plant stands, height of plants, mean number of beans by pod, 1,000 bean mass, number of pods per plant and productivity of the culture were evaluated. The resistance to penetration increased with the levels of soil compaction regardless of the farming year and up to a depth of 0.20 m. In the first crop, higher productivity with the use of the shank was observed. In the second crop, the use of the shank resulted in an increase in depth of the furrow, mobilized soil, height of the plants and final stand of the plants, but this did not indicate an increase in productivity.

RESUMO Quantidades de N proveniente de adubos verdes não absorvidas no primeiro ciclo de cultivo, podem ser absorvidas em cultivos subsequentes. Portanto, é importante quantificar e monitorar o efeito residual da adubação verde visando aumentar o seu benefício agronômico nos sistemas de cultivos. O objetivo do trabalho foi estudar o efeito residual das doses do adubo verde Crotalaria juncea aplicadas no cultivo de brócolis, sobre a sucessão abobrinha italiana-milho. O estudo foi realizado em um sistema de sucessão de culturas organizado em três cultivos, com sete tratamentos, sendo os principais quatro doses de adubo verde: 0, 3, 6 e 9 t ha-1. Os tratamentos testemunhas consistiram de adubação mineral, um tratamento com 25 t ha-1 de composto e um outro como testemunha absoluta, sem composto ou adubação mineral. A parcela experimental constou de cinco linhas espaçadas de 0,8 m com 3 m de comprimento. O delineamento experimental foi de blocos casualizados com quatro repetições no esquema de parcelas subdivididas no tempo para as variáveis de crescimento com ajuste dos modelos estatísticos pela metodologia de superfície de resposta. A produção das plantas de abobrinha na maior dose de adubo verde foi superior à produção das plantas na testemunha com 25 t ha-1 de composto e similar com adubação mineral. A produtividade de milho na dose de 9 t ha-1 de adubo verde foi superior somente à produção da testemunha absoluta. Houve efeito residual da massa Crotalaria juncea, aplicada na cultura do brócolis, sobre o crescimento e a produção de abobrinha e produtividade do milho cultivados em sucessão. O efeito residual é dependente da quantidade de massa de Crotalaria juncea aplicada, com os maiores efeitos nas maiores doses.

ABSTRACT Amounts of N from green manures not absorbed in the first cycle can be absorbed by the subsequent crops. Therefore, it is important to quantify and monitor the residual effects of green manure to increase the agronomic benefits of its use in cropping systems. Our purpose was to study the residual effect of doses of the Crotalaria juncea green manure applied in broccoli crop in the zucchini-maize succession. This study was carried out in a crop succession system organized in three crops, with seven treatments and four major doses of green manure as 0, 3, 6, and 9 t ha-1. The control treatments consisted of a mineral fertilization, a treatment with 25 t ha-1 compost, and another as absolute control without organic compost or mineral fertilizer. The experimental plot consisted of five rows spaced 0.8 m with 3 m in length. The experimental design was a completely randomized block with four replications in a split-plot scheme in time for growth with variables of adjustment of statistical models by the response surface methodology. With the highest dose of green manure, the yield of zucchini plants was greater than the yield with 25 t ha-1 compost control and similar with mineral fertilizer. As for the maize yield in the dose of 9 t ha-1 green manure, the yield was superior only to absolute control. There was a residual effect of C. juncea mass, which was applied in broccoli crop for growth and yield of zucchini and maize grown in succession. The residual effect is dependent on the amount of weight of C. juncea applied, with the greatest effects in larger doses.

A velocidade de operação do trator influencia diversos aspectos, entre eles o consumo de combustível, a capacidade operacional e a qualidade de semeadura. Este trabalho teve como objetivo avaliar a demanda energética de um conjunto trator-semeadora-adubadora em sistema plantio direto, em função das velocidades de deslocamento e rotações no eixo do motor, na semeadura da cultura do milho. Os 12 tratamentos foram constituídos de quatro velocidades de deslocamento, obtidas em função dos escalonamentos de marchas e de três rotações do motor do trator. Durante a semeadura, monitoraram-se a velocidade de operação, a rotação do motor, a força de tração e o consumo horário de combustível. Os resultados mostraram que o requerimento de potência na barra de tração, média, por linha de semeadura, por profundidade do sulco e por área mobilizada aumentou com o aumento da velocidade de operação do conjunto mecanizado. O consumo horário de combustível foi elevado com o aumento da velocidade de operação e da rotação do motor, sendo menor na rotação do motor de 1.500 rpm.

The operating speed of the tractor influences various aspects, including fuel consumption, operational capacity and sowing quality. This study aimed to assess the energy needs of a tractor-planter when sowing maize in a no-tillage system, according to its travel speed and the rotation speed of the motor shaft. The 12 treatments consisted of four travel speeds, obtained by staggering the gears, and three tractor-engine rotation speeds. During sowing, the speed of operation, engine speed, the traction force and hourly consumption of fuel were monitored. The results showed that the average power requirement on the drawbar per seeding row, groove depth, and worked area, increased with an increase in the operating speeds of the mechanism. Hourly fuel consumption went up with the increase in operating and engine-rotation speeds, being lowest at a speed of 1,500 rpm.

A palhada de cobertura residual representa o grande diferencial do sistema de semeadura direta, propiciando melhorias nas condições biológicas, químicas e físicas do solo, em contrapartida esta matéria seca residual pode implicar em dificuldades no processo de semeadura, necessitando por vezes de um manejo deste resíduo. O presente trabalho teve por objetivo avaliar o desenvolvimento e produtividade da cultura do milho submetido a diferentes métodos de manejo de palhada, mecanismos sulcadores e velocidades de operação. Utilizou-se o delineamento em blocos ao acaso com parcelas subsubdivididas, composto por 16 tratamentos e quatro repetições, totalizando 64 unidades experimentais. Os tratamentos foram compostos pela combinação entre quatro manejos de palhada (palha gradeada, rolada, triturada e dessecada), dois mecanismos sulcadores (disco duplo e haste sulcadora) e duas velocidades de semeadura (4,5 e 7,0 km h-1). Avaliou-se a profundidade de deposição de sementes, área de solo mobilizada, uniformidade de distribuição de sementes, estande inicial de plantas, número de fileiras por espiga, número de grãos por fileira, massa de mil grãos e produtividade da cultura. Os dados obtidos foram submetidos às análises de variância e havendo diferenças significativas, as médias foram comparadas pelo teste de Tukey, a 5% de significância. A velocidade de operação de 7,0 km h-1 apresentou valores de espaçamentos falhos e duplos mais elevados. Os tratamentos empregados não influenciaram os componentes de rendimento da cultura, bem como não se observou diferenças significativas para a produtividade média da cultura de milho.

The stubble covering left over represents the biggest difference of the direct seeding cultivation, providing improvement on biological, chemical and physical soil conditions. Nevertheless, the dry matter remaining may difficult the seeding process, demanding additional management of covering. The aim of this study was to evaluate the development and yield of corn cultivation submitted to different methods of stubble management, furrowing machinery and working speed. A block outlining was used at random with sub-divided lots consisting of 16 treatments and four repetitions, totalizing 64 experimental unities. The treatments consisted of a combination between four stubble managements (harrowed, rolled, grinded and desiccated stubble), two furrowing machines (double disc and furrowing shank) and two seeding velocities (4.5 e 7.0 km h-1). Deposition depth was evaluated, as well as mobilized soil area, eeding distribution, initial plant stand, rows per corn spike, grain per row, weight of thousand grains and crop yield. The data were submitted to the analysis of variance and since there were significant differences, the averages were compared by the Tukey test, at 5% of significance. The working speed of 7.0 km h-1 increased faulty and double spacing. The method proposed herein did not affect crop yield and its components.

Um protótipo de máquina coletora de anteras foi projetado e construído, e seu desempenho foi avaliado, comparando - se com o método de coleta manual, em flores rosáceas e campanuladas de pessegueiro (Prunus persica). O trabalho foi conduzido utilizando-se do delineamento experimental inteiramente ao acaso, arranjado em um esquema bifatorial (2 métodos de remoção x 2 formas florais), com 12 repetições de 30 balões florais. O protótipo apresentou maior velocidade de processamento, sem diminuir a qualidade do pólen, mesmo sendo armazenadas anteras com maior quantidade de filetes e descartado maior número de anteras do que o método manual.

An anther collector prototype machine was projected and built. Its performance was evaluated by comparisons between the use of the prototype and the traditional manual method, both for showy and non-showy peach-tree flowers (Prunus persica). The study was accomplished in August 2011 using a completely randomized experimental design, arranged in a bi-factorial scheme (2 collection methods x 2 flower forms), with 12 repetitions, each consisted by 30 flowers. The prototype proved to be faster in the anther extraction time without losses in the pollen quality, even harvesting anthers with higher fillet amounts and discarding a higher quantity of anthers than the manual method.

A precipitação é um elemento meteorológico de grande importância, e seu conhecimento histórico torna-se relevante para o monitoramento de impactos causados pelo seu excesso ou falta prolongados. Objetivou-se, no presente trabalho, analisar a distribuição da precipitação mensal e anual e os níveis de probabilidade de ocorrência de chuvas, utilizando-se o modelo probabilístico de distribuição Gama incompleta, para os dados de precipitação pluviométrica de Cáceres (MT). Utilizou-se uma série de dados de 26 anos, disponibilizada pelo Instituto Nacional de Meteorologia, o qual possui uma estação em Cáceres. A precipitação anual teve grande variabilidade, com mínima de 972,9 mm, em 1985, e máxima de 1.624,1 mm, em 1998. Observou-se, por meio dos dados mensais, que existem duas estações bem definidas, a seca (maio a setembro) e a chuvosa (outubro a abril). As menores médias mensais ocorreram nos meses de junho, julho e agosto, com 16,59 mm, 17,90 mm e 20,09 mm, respectivamente. As estimativas do parâmetro α variaram de 0,9, em junho e agosto, a 13,4, em março. O parâmetro β variou de 13,2, em março, a 33,1, em janeiro. O período com maior probabilidade de precipitação vai de dezembro a março, enquanto junho, julho e agosto foram os meses em que a probabilidade de ocorrência de precipitação foi mais baixa.

Rainfall is an important meteorological element, and the knowledge on its historical records is relevant for monitoring the impacts caused by its prolonged excess or lack. This study aimed to evaluate the monthly and annual rainfall variability and the probability for its occurrence, by using the incomplete Gamma distribution model, for the rainfall data from Cáceres, Mato Grosso State, Brazil. A series of 26 years data, provided by the National Institute of Meteorology, which supports a station in Cáceres, was used. The annual rainfall amounts showed great variability, with minimum of 972.9 mm, in 1985, and maximum of 1,624.1 mm, in 1998. The monthly data pointed out two well defined seasons: the dry season (May to September) and the rainy one (October to April). The lowest monthly averages occurred in June, July, and August, with 16.59 mm, 17.90 mm, and 20.09 mm, respectively. The estimates for the α parameter ranged from 0.9, in June and August, to 13.4, in March. The β parameter ranged from 13.2, in March, to 33.1, in January. The highest rainfall probability takes place from December to March, while June, July, and August show the lowest rainfall probability.

A integração lavoura-pecuária pode ser definida como o sistema que integra duas atividades, visando a maximizar racionalmente o uso da terra e a minimizar os custos de produção. Objetivou-se, com este trabalho, avaliar os efeitos de diferentes alturas remanescentes de pastagem e de mecanismos sulcadores sobre o desenvolvimento inicial e a produtividade da cultura do milho semeado em sequência. Os tratamentos foram compostos pela combinação de quatro intensidades de pastagem (0,05; 0,15; 0,30 m e sem pastejo) e de dois mecanismos sulcadores (haste e disco), utilizados na semeadura pós-pastejo. Após a semeadura, foram avaliados a profundidade de deposição das sementes, o índice de velocidade de emergência de plântulas, o estande final de plantas, a altura inicial e de inserção de espigas e o rendimento de grãos. As diferentes intensidades de pastagem influenciaram significativamente a profundidade de deposição de sementes, a altura inicial de plantas e de inserção da primeira espiga e a produtividade, sendo que a altura de pasto remanescente de 0,05 m apresentou os menores valores de profundidade de deposição de sementes, quando comparada com os demais níveis. Os diferentes mecanismos sulcadores influenciaram apenas a profundidade de deposição de sementes.

Crop-livestock systems may be defined as the integration of two activities aiming to rationally maximize the land use and to decrease production costs. The objective of this study was to evaluate the effects of different heights of remaining pasture and seed drills on the yield of corn grown in sequence. The treatments consisted of combinations of four remaining pasture residue heights (0,05; 0,15; 0,30 m and ungrazed) and two planter furrow openers on seed drills (shoe and disk), used for seeding after grazing. After corn sowing, the depth of seed deposition, the rate of seedling emergence, initial stand of plants, initial and final plant height and crop yield were evaluated. The different grass heights .significantly influenced the depth of seeding, the initial height and insertion of first cob and grain yield. Pasture height of 0,05 m corresponded to the lowest seed depth when compared with the other heights. The different furrow openers affected only the depth of seeding.