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UTFPR, CNPQ, IAPAR / A intensidade de pastejo em áreas de plantio direto apresenta influência direta sobre o rendimento do sistema integração lavoura-pecuária por afetar a produção animal e vegetal, tanto positiva quanto negativamente. Estes efeitos podem ser amenizados pelo uso de semeadoras-adubadoras de plantio direto dotadas de diferentes mecanismos sulcadores que podem interagir a favor da planta cultivada otimizando a sua produtividade. Diante disso, este trabalho teve por objetivo avaliar diferentes intensidades de pastejo e a influência de mecanismos sulcadores sobre o desenvolvimento do milho no sistema de integração lavoura-pecuária. Utilizou-se delineamento em blocos ao acaso em parcelas subdivididas com quatro repetições. As parcelas principais constituíram as diferentes intensidades de pastejo (Sem Pastejo; 35 x 15; 30 x 10 e 25 x 5 cm, respectivamente para as alturas de entrada e saída dos animais dos piquetes) e nas subparcelas os dois mecanismos sulcadores (facão e disco duplo). Para ajuste das alturas de pastejo foram utilizadas vacas da raça holandesa com peso vivo médio de 500 kg em pastejo intermitente. As alturas de entrada e saída dos animais da pastagem diferiram entre todas as intensidades de pastejo. A caracterização física do solo foi realizada antes e após o período de pastejo (96 dias de pastejo). Após a semeadura do milho, para a avaliação da influência das diferentes intensidades de pastejo e dos mecanismos sulcadores, os seguintes parâmetros foram analisados: profundidade de deposição de sementes, área de solo mobilizada, índice de velocidade de emergência, diâmetro de colmo, altura de plantas, altura de inserção da primeira espiga, componentes de rendimento e produtividade. De acordo com os resultados obtidos, pode-se concluir que: A taxa de acúmulo da aveia teve valores de 56,75; 41,9; 41,31 e 32,74 kg de MS ha-1 dia-1, e a produção total foi de 7.548, 5.531, 5.494 e 4.322 kg de MS ha-1, respectivamente para os tratamentos Sem Pastejo, 35 x 15, 30 x 10 e 25 x 5 cm. As intensidades de pastejo afetaram a densidade do solo, sendo os maiores valores encontrados nas maiores intensidades. A área de solo mobilizada e a profundidade de semeadura diferiram entre mecanismos sulcadores, apresentando valores superiores quando se utilizou o sulcador facão. A dinâmica da produção do milho foi afetada pelas intensidades de pastejo e pelos mecanismos sulcadores. Para o mecanismo sulcador tipo disco, a produtividade diminui linearmente com o aumento das intensidades de pastejo, apresentando diferença de 942 kg ha-1 entre os tratamentos Sem Pastejo e a maior intensidade de pastejo (25 x 5 cm). Esta diferença foi amenizada com o uso do mecanismo sulcador facão, caindo para 324 kg ha-1, no entanto, este tratamento (25 x 5 cm) apresentou produtividade inferior às demais intensidades de pastejo, comprovando o efeito negativo de altas intensidades de pastejo sobre a densidade do solo e a produtividade da pastagem e do milho. / Grazing intensity in no-till areas influences the yield of the crop-livestock system both positively or negatively. Furthermore, these effects can be mitigated by the use of notill seed planter equipped with different drills which can interact in favor of the crops optimizing its productivity. Thus, this study aimed to evaluate different grazing intensities and the influence of seed drills on the development of the corn crop in integrated crop-livestock. The experiment was laid out as random block design in a split-plot design with four replications. Main plots refer to the grazing intensities (ungrazed, 35 x 15, 30 x 10 and 25 x 5 cm of height respectively to the entrance and exit of the animal from the paddocks) and the subplots, the seed drills (double disc and knife). To adjust the wanted forage heights were used dairy cows with average live weight of 500 kg with an intermittent grazing. Real pasture heights of entrance and exit of animals from pasture differed among all grazing intensities. Soil traits were evaluated before and after the grazing period (96 days). After the corn sowing, to evaluate the influence of different grazing intensities and seed drills, the following parameters were assessed: depth of seed deposition, soil area mobilized, rate of emergence, stem diameter, height of plants and height of first ear, yield components and productivity. According to the results, it can be concluded that: Forage accumulation rate showed values of 56.75, 41.9, 41.31 and 32.74 kg of MS ha-1 d-1, and total production was of 7,548, 5.531, 5,494 and 4,322 kg ha-1 of DM respectively for the ungrazed treatment, 35 x 15, 30 x 10 and 25 x 05 cm. Grazing intensities affected the soil density. The area of mobilized soil and seeding depth differed between seed drills being higher to the knife drill. Corn grain yield dynamics were affected by the grazing intensities and seed drills. Corn yield decreased as the grazing intensities increased to the double disc seed drill mechanism with a difference of 942 kg ha-1 between the treatments without grazing and the highest grazing intensity (25 x 5 cm). The use of knife seed drill reduced this difference to 324 kg ha-1, however, this treatment (25 x 5 cm) showed lower productivity than the other grazing intensities, confirming the negative effect of high grazing intensities over the soil density and forage and crops yield.

UTFPR, CNPQ, IAPAR / A intensidade de pastejo em áreas de plantio direto apresenta influência direta sobre o rendimento do sistema integração lavoura-pecuária por afetar a produção animal e vegetal, tanto positiva quanto negativamente. Estes efeitos podem ser amenizados pelo uso de semeadoras-adubadoras de plantio direto dotadas de diferentes mecanismos sulcadores que podem interagir a favor da planta cultivada otimizando a sua produtividade. Diante disso, este trabalho teve por objetivo avaliar diferentes intensidades de pastejo e a influência de mecanismos sulcadores sobre o desenvolvimento do milho no sistema de integração lavoura-pecuária. Utilizou-se delineamento em blocos ao acaso em parcelas subdivididas com quatro repetições. As parcelas principais constituíram as diferentes intensidades de pastejo (Sem Pastejo; 35 x 15; 30 x 10 e 25 x 5 cm, respectivamente para as alturas de entrada e saída dos animais dos piquetes) e nas subparcelas os dois mecanismos sulcadores (facão e disco duplo). Para ajuste das alturas de pastejo foram utilizadas vacas da raça holandesa com peso vivo médio de 500 kg em pastejo intermitente. As alturas de entrada e saída dos animais da pastagem diferiram entre todas as intensidades de pastejo. A caracterização física do solo foi realizada antes e após o período de pastejo (96 dias de pastejo). Após a semeadura do milho, para a avaliação da influência das diferentes intensidades de pastejo e dos mecanismos sulcadores, os seguintes parâmetros foram analisados: profundidade de deposição de sementes, área de solo mobilizada, índice de velocidade de emergência, diâmetro de colmo, altura de plantas, altura de inserção da primeira espiga, componentes de rendimento e produtividade. De acordo com os resultados obtidos, pode-se concluir que: A taxa de acúmulo da aveia teve valores de 56,75; 41,9; 41,31 e 32,74 kg de MS ha-1 dia-1, e a produção total foi de 7.548, 5.531, 5.494 e 4.322 kg de MS ha-1, respectivamente para os tratamentos Sem Pastejo, 35 x 15, 30 x 10 e 25 x 5 cm. As intensidades de pastejo afetaram a densidade do solo, sendo os maiores valores encontrados nas maiores intensidades. A área de solo mobilizada e a profundidade de semeadura diferiram entre mecanismos sulcadores, apresentando valores superiores quando se utilizou o sulcador facão. A dinâmica da produção do milho foi afetada pelas intensidades de pastejo e pelos mecanismos sulcadores. Para o mecanismo sulcador tipo disco, a produtividade diminui linearmente com o aumento das intensidades de pastejo, apresentando diferença de 942 kg ha-1 entre os tratamentos Sem Pastejo e a maior intensidade de pastejo (25 x 5 cm). Esta diferença foi amenizada com o uso do mecanismo sulcador facão, caindo para 324 kg ha-1, no entanto, este tratamento (25 x 5 cm) apresentou produtividade inferior às demais intensidades de pastejo, comprovando o efeito negativo de altas intensidades de pastejo sobre a densidade do solo e a produtividade da pastagem e do milho. / Grazing intensity in no-till areas influences the yield of the crop-livestock system both positively or negatively. Furthermore, these effects can be mitigated by the use of notill seed planter equipped with different drills which can interact in favor of the crops optimizing its productivity. Thus, this study aimed to evaluate different grazing intensities and the influence of seed drills on the development of the corn crop in integrated crop-livestock. The experiment was laid out as random block design in a split-plot design with four replications. Main plots refer to the grazing intensities (ungrazed, 35 x 15, 30 x 10 and 25 x 5 cm of height respectively to the entrance and exit of the animal from the paddocks) and the subplots, the seed drills (double disc and knife). To adjust the wanted forage heights were used dairy cows with average live weight of 500 kg with an intermittent grazing. Real pasture heights of entrance and exit of animals from pasture differed among all grazing intensities. Soil traits were evaluated before and after the grazing period (96 days). After the corn sowing, to evaluate the influence of different grazing intensities and seed drills, the following parameters were assessed: depth of seed deposition, soil area mobilized, rate of emergence, stem diameter, height of plants and height of first ear, yield components and productivity. According to the results, it can be concluded that: Forage accumulation rate showed values of 56.75, 41.9, 41.31 and 32.74 kg of MS ha-1 d-1, and total production was of 7,548, 5.531, 5,494 and 4,322 kg ha-1 of DM respectively for the ungrazed treatment, 35 x 15, 30 x 10 and 25 x 05 cm. Grazing intensities affected the soil density. The area of mobilized soil and seeding depth differed between seed drills being higher to the knife drill. Corn grain yield dynamics were affected by the grazing intensities and seed drills. Corn yield decreased as the grazing intensities increased to the double disc seed drill mechanism with a difference of 942 kg ha-1 between the treatments without grazing and the highest grazing intensity (25 x 5 cm). The use of knife seed drill reduced this difference to 324 kg ha-1, however, this treatment (25 x 5 cm) showed lower productivity than the other grazing intensities, confirming the negative effect of high grazing intensities over the soil density and forage and crops yield.

Thesis (Ph.D. (Plant Production)) -- University of Limpopo, 2022 / Sustainable food production has been a major challenge in the era of climate change and a growing population in the twenty-first century. However, climate change scenarios such as extreme temperatures and fluctuations in annual precipitation continue to pose a great threat to agricultural production systems. On the other hand, anthropogenic activities such as conventional farming continue to contribute to climate change through the emission of greenhouse gases while not sustaining agricultural production. The Food and Agriculture Organization of the United Nations (FAO-UN) developed the concept of Climate-Smart Agricultural (CSA) production with the idea of securing food in the face of global change. No-tillage and intercropping systems are among the traditional practices that are advocated as components of climate-smart traditional practices, especially in the semi-arid regions of Africa like the Limpopo Province. Producing sorghum and cowpeas using CSA practices such as intercropping under no-tillage is envisaged to increase productivity and soil fertility under Limpopo Province's dryland conditions. However, there is still limited information on how grain sorghum-cowpea intercrop will respond in terms of growth, physiological productivity, and carbon dioxide emissions in the system, especially under no-tillage and different growing conditions. Furthermore, more field data is required for predictions of future scenarios using simulating crop models such as the Agricultural Production system sImulator (APSIM). Hence, a no-till Randomized Complete Block Design (RCBD) in a 2 x 4 x 2 factorial arrangement was conducted at two locations (Syferkuil and Ofcolaco) in the Limpopo Province during the 2018/19 and 2020/21 cropping seasons to generate data on sorghum and cowpea growth, physiology, productivity as well as carbon dynamics under planted and simulated intercropping system. Leaf gaseous exchange and leaf area index (LAI) were measured on fully developed grain sorghum and cowpea leaves in both the binary and sole cultures of sorghum and cowpea. The CO2 measurements were taken from each plot using a GMP343 CO2 probe along with an MI70 data logger. Aboveground biomass was collected for each crop from two plants at vegetative, flowering, physiological and harvest maturity and oven-dried at 65 oC for 48 hours. In the 2020/21 cropping season, cowpea at Ofcolaco failed to produce grain. Hence, only the grain yield of the 2018/19 cropping season from Ofcolaco is presented in this thesis. Grains collected for each crop from a 2.7m2 area were taken to the laboratory to determine grain yield and yield components. Harvest index (HI) and land equivalent ratio (LER) for each crop were also determined. In the laboratory, the total nitrogen (%) and natural abundance of 15N (δ15N‰) were determined using an isotope ratio mass spectrometer with an N analyzer. Growth (biomass) and yield (grain) data obtained from APSIM were compared with data collected from a two-year field experiment at Syferkuil. Multi-variate analysis of variance (ANOVA) model to fit each response variable using the Statistical Analysis System (21 SAS version 9.4). Mean separation was done where the means were different using the least significant difference (LSD) at probability levels of p ≤ 0.05. Intercropping system and the density of the companion crop cowpea had a significant (p ≤ 0.05) effect on the physiological responses of sorghum and cowpea, cowpea yield and yield components at the two experimental sites across seasons. However, grain yield and yield components of sorghum were not affected by intercropping or the density of cowpea. Only cultivars of sorghum were significantly different for grain yield and yield components. At Syferkuil, Enforcer produced the highest grain yield of 4338 kg ha-1 in 2018/19, while NS5511 accumulated the highest grain yield of 2120 kg ha-1 during the 2020/21 cropping seasons. At Ofcolaco, Enforcer and Avenger were observed to be relatively high-yielding cultivars with a mean grain yield of 2625 kg ha- 1 and 1191 kg ha-1 during the 2018/19 and 2020/21 cropping seasons, respectively. In the 2018/19 and 2020/21 cropping seasons, respectively, cowpea accumulated about 93% and 77% more grain yield in sole compared to binary culture. At Ofcolaco, about 96% more grain yield was obtained in sole compared to binary cultures during the 2018/19 cropping season. Furthermore, cowpea accumulated over 55% and 49% of grain yield when grown at high compared to low population density at Syferkuil and Ofcolaco, respectively. The investigation on the impact of the intercropping system on CO2 emissions and soil carbon stocks revealed that in 2018/19 at Syferkuil and 2020/21 at Ofcolaco, intercropping systems emitted 11% and 19% less CO2 respectively than the sole cropping systems. In both diverse agro-ecological sites, low cowpea density consistently resulted in higher CO2 emissions than high density. The sorghum-cowpea intercropping system significantly influenced the biological nitrogen fixation of cowpea. Intercropping was found to improve the biological nitrogen fixation of cowpea if a density of 74074 plants ha-1 is used. The APSIM model was able to capture the dynamics of biomass and grain yields in the sole and intercropping system under different densities of cowpea. The findings of this study revealed some useful insights. Firstly, biomass accumulation depended on the cultivar in intercrop as well as the density of cowpea. Secondly, cowpea at a density of 74074 plants ha1 was found to be a good crop to intercrop with grain sorghum as it did not show any significant variation in terms of grain yield and yield components of sorghum. The sorghum cultivar, Enforcer and NS5511 were the best performing cultivars in terms of grain yields at Syferkuil and Ofcolaco. Thirdly, the intercropping system under high cowpea density reduced CO2 emission rates while improving soil nitrogen (N) and carbon stocks. Based on the results of this study, grain sorghum-cowpea intercrop can be adopted as a component of a climate-smart practice to improve crop growth, physiology, as well as productivity compared to sole cropping. However, the grain sorghum cultivar and the density of cowpea should be taken into consideration as they affect the productivity of the two crops. The two seasons data generated from this study was useful in simulating the productivity of intercropping practice using APSIM. However, more field and weather data is required to run long-term simulations on intercropping as a component of the climate-smart method using crop modelling techniques. / National Research Foundation (NRF), Departments of Science and Innovation (DSI) and VLIR-IUC (Belgium)