ABSTRACT This study aimed to model nutrient losses in an Oxisol under varied soil properties and vegetation cover. The experimental area was located at the Paraná Rural Development Institute, in Santa Tereza do Oeste, Paraná, Brazil. The treatments consisted of six cover crops in summer, six cover crops in winter, and management systems no-tillage (NT) traditional (control), NT with gypsum, and NT with scarification. Nutrient data were collected at each natural rainfall through sample collection from collection troughs. The design was completely randomized, and the data were adjusted using an exponential function of two variables, as a function of soil density, macroporosity, straw dry mass, green cover, and rainfall. Greater losses of Mg and Ca was related to higher soil density and lower macroporosity. Lower losses of Mg, Ca, K, and P were associated with lower straw dry mass and higher green cover. K and P losses were stable for all soil density values, but they decreased with an increase in macroporosity.

ABSTRACT The combination of crambe (Crambe abyssinica L.) biodiesel and biogas could be a renewable energy alternative for internal combustion engines. Therefore, the emissions and engine performance of crambe biodiesel blends (B0, B10, B30, B50, B75, and B100) were evaluated in both the dual mode (biogas) and normal mode (biodiesel). The tests were performed on a 5-kVA generator engine at loads ranging from 1 to 4 kW. The power generated in the normal mode was 17% lower than that generated in the dual mode. The dual mode showed a lower specific fuel consumption than the normal mode. In the normal mode, loss of power occurred as the proportion of biodiesel increased. Furthermore, nitrogen oxide emissions decreased with the addition of biogas. In the dual mode, the emissions increased as the biodiesel content increased. Carbon monoxide emissions decreased in both the normal and dual modes with an increase in biodiesel. The addition of biogas in the dual fuel mode with crambe biodiesel is an efficient alternative for partial substitution of diesel.

ABSTRACT. The screening of cover crops is essential for improving the physical-hydric properties of compacted soils. This study aimed to evaluate the effects of mixed or single cover crops on improving the physical-hydric properties of compacted Oxisol. Species with tap-rooted and fibrous-rooted rooting patterns were evaluated. The species included pearl millet (Pennisetum americanum), pigeon pea (Cajanus cajan), sunn hemp (Crotalaria spectabilis), velvet bean (Mucuna pruriens), white oat (Avena sativa), black oat (Avena strigosa), rye (Secale cereale), black oat + forage turnip (Raphanus sativus), black oat + white lupin (Lupinus albus L.), and black oat + group pea (Pisum arvense L.). Mixing cover crops did not improve the physical properties of the soil. The tap-rooted pigeon pea effectively reduces bulk density and increases porosity and saturated hydraulic conductivity (Ksat) in compact soils. The selection of cover crops with characteristics that improve soil physical-hydric properties is crucial for compacted areas.

ABSTRACT Sesame ( Sesamum indicum L.) oilseed needs to be studied in relation to the production of biodiesel and its application as an alternative to the soybean biodiesel used in Brazil. The aim of this study was to evaluate biodiesel blends (B0, B5, B10, B20, B40, B80, and B100) of sesame in the performance and emissions of engines. A few studies of sesame biodiesel in engines were found in the literature imparts novelty to the current study. The fuels were tested in a 5-kVA generator engine at loads ranging from 1000 to 6000 W. The results of the analysis showed that the increase in the sesame biodiesel blend caused a reduction in the specific fuel consumption (SFC), carbon monoxide (CO) emissions, and an increase in nitrogen oxide (NOx) emissions. The SFC of sesame biodiesel (B100) was 11% higher than that of diesel (B0). CO emissions increased 39% for diesel (B0) compared to sesame biodiesel (B100). However, B20 showed lower SFC than diesel and lower gas emissions than B80 and B100 blends. Therefore, sesame biodiesel, especially up to B20, is a viable alternative for the partial replacement of conventional diesel. Sesame biodiesel should be considered as a promising candidate for alternative fuels.

ABSTRACT Different mechanical configurations of diesel engines, when powered by biogas, can influence engine performance and efficiency. Consequently, this study aims to evaluate various generator engines to determine the optimal configuration for a distributed generation unit at a swine farm. In this study, we assess the biogas consumption, specific consumption, and efficiency of five biogas generator engines. Three engines (A, D, and E) were provided by Biogás Motores Estacionários, while the remaining two (B and C) were provided by Electro Hager models and MWM, respectively. The biogas used was produced in plug flow biodigesters (piston flow) by the treatment of swine waste. Engine A, provided by Biogás Motores Estacionários, exhibited specific consumption at a power of 30 kW (low load) similar to engines B and C. However, engines B and C displayed higher efficiencies at high loads compared to engines A, D, and E, attributed to their advanced fuel injection and control systems.

ABSTRACT Furrowing shank horizontal strength and working depth can be correlated with soil compaction in a no-till sowing. This study aimed to evaluate the correlation of furrowing shank strength and working depth with soil physical properties at two working speeds (1.58 and 1.87 m s-1) and four compaction levels induced by an agricultural tractor (0P, 1P, 3P, and 5P+Ballast), with four repetitions in an RBD. Thereby, we aimed to verify a potential increase in sampling density of soil compaction data. Horizontal strength at 1.58 m s-1 had Pearson correlations ranging from 0.74 to 0.73 with soil penetration resistance (SPR), and from 0.57 to 0.72 with some soil properties collected by volumetric ring. Working depth also correlated with several parameters ranging from 0.49 to 0.81. The highest correlations were verified for the speed of 1.58 m s-1, at which shanks maintained greater depth. This increased soil contact with the shank, hence sensitivity to compaction. Our findings show that furrowing shank horizontal strength and working depth can be used to monitor soil compaction.

RESUMO: O cártamo (Carthamus tinctoriusL.) apresenta flores e frutos irregulares, o que pode causar problemas na produção e colheita de sementes em regiões com clima quente e úmido. No entanto, pouco se sabe sobre o tempo ideal de colheita de cártamo. Portanto, o objetivo desteestudo foi avaliar o momento ideal para a colheita de sementes de três genótipos de cártamo(2106, S-325 e 7329). O experimento foi delineado em blocos casualizados, com seis repetições. A colheita começou 16 dias após o florescimento (DAF) e terminou aos 52 DAF. Dez colheitas foram feitas no total. Foram avaliados o teor de água das sementes, matéria fresca e seca das sementes, germinação das sementes e primeira contagem de germinação. Os genótipos 2106 e 7329 tiveram taxas de germinação de 79% e 91%, respectivamente, aos 34 e 38 dias após a floração (DAF), enquanto o genótipo S-325 teve 90% de germinação aos 37 DAF. A colheita aos 52 DAF combinada com uma estação chuvosa prejudicou a germinação das sementes de cártamo. A época de colheita mais adequada para o cártamo ocorreu entre 34 e 42 DAF, quando as sementes apresentam teor de água entre 26% e 33%.

ABSTRACT: The safflower (Carthamus tinctoriusL.) has an uneven flowering and fruiting, which can cause problems in seed production and harvesting in regions with hot and humid climates. However, little is known about the optimal safflower harvest time. Therefore, this study evaluated the optimumtiming for seed harvest of three safflower genotypes (2106, S-325, and 7329).The experiment was a randomized complete block design with six replications. The harvest started 16 days after flowering (DAF) and ended at 52 DAF. Ten harvests were made in total. Seed water content, seeds fresh and dry matter, seed germination, and first germination counts were evaluated.Genotypes 2106 and 7329 had germination rates of 79% and 91%, respectively, at 34 and 38 DAF, while genotype S-325 had 90% germination at 37 DAF. Harvesting at 52 DAF combined with a rainy season impaired the germination of safflower seeds. The harvest time most suitable for safflower occurred between 34 and 42DAF, when the seeds have the seed water content between 26% and 33%.

ABSTRACT Brassica oilseed species are becoming increasingly popular for industrial uses, with emphasis on biodiesel. It is of importance to evaluate the yield and oil production potential of nontraditional oilseeds for use as feedstock in Brazil. In this study, growth, yield, and oil content and their correlations were determined for eight accessions of B. juncea and B. rapa in two years under tropical conditions of southeastern Brazil. Significant variation was observed between B. juncea and B. rapa accessions for yield components and oil content. B. rapa was the earliest maturing and had the highest oil content, whereas B. juncea had the highest number of pods and the highest yield and oil yield. Brassica rapa accessions flowered early, with an average cycle of 97 days, whereas B. juncea reached maturation after 110 days on average. Accessions were grouped according to the oil content of each species, with the most promising accessions having an oil content of 45–47%. Accessions of Brassica species had high oil yields, reaching 910 kg ha-1 of oil yield for B. juncea PI 180266. There was a linear correlation between oil content and thousand seed weight, pod length, and seeds per pod of the Brassica species accessions. Considering oil content and oil yield across years, Brassica species show promise as alternative oilseed crops for biodiesel production in tropical conditions.

ABSTRACT Safflower (Carthamus tinctorius L.) is a commercial seed crop grown for its good yield of high-quality oil. It is tolerant to water stress but may be sensitive to soil compaction. The aim of this study was to assess safflower growth under different degrees of soil compaction at depths of 0.15 m to 0.20 m. The experiment was carried out in PVC pots constructed from three rings. Five levels of penetration resistance (0.20, 0.33, 0.50, 0.93, and 1.77 MPa) were applied in the intermediate ring, and two safflower genotypes, IMA-4904 and IMA-2106, were examined. There was no difference between safflower genotypes with respect to their resistance to soil compaction, which reduced root length density in the compacted layer and changed the root distribution in the soil profile, but did not prevent the roots from crossing the compacted layer and developing in depth. Increased soil bulk density in the compacted layer increased root diameter of the IMA-2106 genotype. Penetration resistance levels over 0.20 MPa (density of 1.2 mg.dm–3) limited safflower root development. The maximum safflower growth occurred when the soil penetration resistance was 0.86 MPa. In this study, the Q1/2 index was higher than 1.77 and 1.55 for the IMA-2106 and IMA-4904 genotypes, respectively. Hence, safflower has proven to be tolerant to soil compaction, and stands out as a species with potential to decrease soil bulk density.

Resumen En función de su origen y rusticidad, el cártamo se produce generalmente en tierras secas, de baja fertilidad, con pocos insumos y sin riego. En Brasil, poco se sabe de la respuesta de este cultivo a la aplicación de nitrógeno (N) y al riego. Este estudio fue realizado próximo a Ingeniero Coelho, SP, Brasil, en la campaña agrícola de 2014, para determinar el efecto de dosis crescientes de nitrógeno (0; 50; 100; 150; 200; 250; 300; 350: 400; 450; 500; 550 e 600 kg.haD1) en el cultivo de cártamo en secano e irrigado. La aplicación de riego en periodos secos, posibilitó reducir el estrés y así, aumentar de forma significativa los componentes de producción y el rendimiento de granos. La producción de cártamo es influenciada por la interacción entre el régimen hídrico y la dosis de nitrógeno. El rendimiento del grano puede variar dependiendo de varios factores, sin embargo, el rendimiento máximo se logró con tasas de 208 y 214 kg.N ha-1 en condiciones de riego y de secano, respectivamente. Para el rendimiento de aceite, 200 kg N. ha-1 fueron suficientes, independientemente del régimen hídrico.

Abstract Due to its origin and hardiness, safflower is usually cultivated in low-fertility soils with few inputs and no irrigation. In Brazil, little is known about its response to nitrogen (N) and irrigation. This study was carried out near the city of Engenheiro Coelho, SP, Brazil, in 2014, in order to determine the effect of increasing nitrogen application rates (0, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550 and 600 kg ha-1) on safflower cultivation under irrigation and rainfed conditions. The use of irrigation during drought periods allowed stress reduction and significantly increased yield components and grain yield. Safflower yield was influenced by the interaction between water regimes and nitrogen rates. Grain yield may vary depending on several factors, however, maximum yield was achieved with rates of 208 and 214 kg N ha-1 under irrigation and rainfed conditions, respectively. For oil yield, 200 kg N ha-1 were sufficient, regardless of the water regime.

RESUMO O guar (Cyamopsis tetragonoloba L.) é comumente cultivado em terras áridas, por ser altamente tolerante à seca. No entanto, a compactação do solo pode ser um fator limitante ao seu cultivo. Objetivou-se avaliar o crescimento de guar, em função da resistência do solo à penetração (0,20 Mpa; 0,33 Mpa; 0,50 Mpa; 0,93 Mpa; e 1,77 Mpa, em camada com profundidade entre 0,15 m e 0,20 m), em Latossolo Vermelho Distroférrico. Avaliaram-se a massa seca da parte aérea e raiz, o comprimento radicular a partir do índice Q1/2 (resistência mecânica do solo à penetração na qual o crescimento radicular é reduzido à metade) e o diâmetro radicular. O crescimento da parte aérea de guar começa a ser prejudicado por resistência superior a cerca de 1 MPa. A compactação do solo altera a distribuição das raízes de guar no perfil do solo, concentrando-as na camada de 0,15 m, mas não impede que as raízes penetrem nessa camada e se desenvolvam em profundidade. O diâmetro de raiz aumenta na camada compactada. A resistência à penetração no solo de até 1,77 MPa não influencia na densidade de comprimento radicular abaixo da camada compactada, bem como na densidade de comprimento radicular total de guar. Embora o índice Q1/2 de guar seja superior a 1,58, a massa seca da parte aérea e da raiz são prejudicadas.

ABSTRACT Guar (Cyamopsis tetragonoloba L.) is commonly grown in arid lands, because of its high drought-tolerance. However, soil compaction may be a limiting factor to its growth. This study aimed to evaluate the guar growth, according to the soil penetration resistance (0.20 MPa, 0.33 MPa, 0.50 MPa, 0.93 MPa and 1.77 MPa, in a layer with depth between 0.15 m and 0.20 m), in a Rhodic Acrudox soil. The shoot and root dry mass, root length by the Q1/2 index (mechanical soil penetration resistance in which the root growth is reduced by 50 %) and root diameter were evaluated. The impairment of the guar shoot growth begins when the penetration resistance is greater than around 1 MPa. The soil compaction alters the distribution of guar roots in the soil profile, concentrating them in the 0.15 m layer, but it does not prevent roots from penetrating this layer and developing in depth. The root diameter increases in the compacted layer. A soil penetration resistance of up to 1.77 MPa does not influence the root length density below the compacted layer, as well as the total root length density of guar. Although the guar Q1/2 index is greater than 1.58, the shoot and root dry mass are impaired.

ABSTRACT Crambe has great potential for cultivation in tropical regions, but its biotic factors may be a limiting aspect for its production. Thus, we aimed in this study to assess the effect of pre‐sowing seed treatments on seedling emergence, root system, production components, and oil. The experiment was conducted during two years in Cascavel, Paraná, Brazil. The experimental design consisted of randomized blocks with six treatments, including a control treatment (no treatment), biological treatments (Trichoderma asperellum and Bacillus subtilis), and chemical treatments (glutamic acid, thiamethoxam and zinc), with four replications. Emergence and growth crambe, as well as production components and oil in the first year were higher due to the contrast in the agricultural years. In the first year, the chemical treatment with thiamethoxam stood out for emergency of plants. Seed treatments did not influence the growth of the aerial parts of the plants, but provided an increase in the root system, especially zinc. Biological (T. asperellum and B. subtilis) and chemical (thiamethoxam) seed treatments led to higher crambe yield when compared to the control treatment; however, the biological treatment with T. asperellum provided less oil.