ABSTRACT Brazil stands out worldwide for its high grain production in areas of direct sowing. The objective of this study was to simulate and assess the relationship of soil organic carbon content and nitrogen, crop yield, and biomass of two crop sequences under the no-tillage system in a subtropical region of São Paulo, Brazil, using CSM-CROPGRO-Soybean and CSM-CERES-Maize models. The modeling was carried out considering the meteorological conditions of Jaboticabal, SP, Brazil. The treatments consisted of combining two summer crops (maize and soybean) with maize cultivation as a winter crop. The average biomass and productivity for corn were 15594 kg ha−1 and 5996 kg ha−1, respectively, and for soybeans they were 5905 kg ha−1 and 3441 kg ha−1, respectively. For soil organic carbon and nitrogen, a small variation was observed between years, and in addition there was a decline in their levels after a year with low biomass production. In our study, the RMSE and MAPE values between the observed and simulated productivity by the model were 2.21 kg ha−1 and 44.24%, respectively. The analysis of main components for the cultivation of corn explained 83.9% of the variability, and for the cultivation of soy, 93.5%. Among the tested models, the CROPGRO was the one with the best accuracy.

RESUMO A cultura do manjericão (Ocimum basilicum) é de grande importância para o comércio como condimento fresco ou seco, para consumo humano e óleo essencial para as indústrias farmacêutica e cosmética. Os excessos e déficits de água podem afetar a produção de biomassa das plantas, tornando necessário o uso da quantidade correta de água para cada cultura. Considerando que as determinações do consumo de água e dos coeficientes de cultivo para plantas medicinais são escassas, o objetivo deste estudo foi determinar a evapotranspiração e os coeficientes de cultivo de manjericão usando lisímetros. A evapotranspiração da cultura foi determinada por lisímetros de pesagem para as reposições de 100, 75 e 50% da evapotranspiração máxima diária. A evapotranspiração de referência da cultura foi estimada pela equação de Penman-Monteith. A evapotranspiração das culturas para o ciclo de 49 dias foi de 471, 352 e 236 mm, e as taxas diárias variaram de 4,8 a 9,4; 4 a 8,1 e 3,7 a 7,4 mm/dia, para as reposições de 100, 75 e 50% da evapotranspiração máxima diária. Os coeficientes de cultivo variaram de 1,5 a 2,8 e foram relacionados aos dias após o transplante, índice de área foliar, razão de cobertura e graus-dia acumulados.

ABSTRACT The basil (Ocimum basilicum) crop is of great importance for trading as fresh or dried condiment for human consumption and essential oil for pharmaceutical and cosmetic industries. Water excesses and deficits can affect biomass production of plants, making it necessary to use the correct amount of water for each crop. Considering that determinations of water consumption and cultivation coefficients for medicinal plants are scarce, the aim of this study was determining evapotranspiration and crop coefficients of basil using lysimeters. The crop evapotranspiration was determined by weighing lysimeters for the replacements of 100, 75 and 50% of the maximum daily evapotranspiration. The reference crop evapotranspiration was estimated by the Penman-Monteith equation. Crop evapotranspiration for the 49 day cycle was 471, 352 and 236 mm, and daily rates ranged from 4.8 to 9.4; 4 to 8.1 and 3.7 to 7.4 mm/day, for the replacements of 100, 75 and 50% of the maximum daily evapotranspiration. Crop coefficients varied from 1.5 to 2.8 and were related to the days after transplanting, leaf area index, cover ratio and cumulative degrees-day.

ABSTRACT: Simulation models of crop growth enable estimating crop yield and water balance components with low cost and high precision. This study aimed to calibrate and evaluate the performance of the CS-CROPGRO model for common beans under the conditions of Jaboticabal city (SP), Brazil. The model was calibrated and tested with data previously collected from two experiments conducted in 2002 and 2003. In these experiments, treatments corresponded to two irrigation scheduling methods (tensiometers and class A pan evaporation) and two cropping systems (conventional and no-till). For calibration, data from the experiment carried out in 2002 were used. For testing, we used data from the experiment conducted in 2003. By using the genetic coefficients calibrated for cultivar IAC-Carioca, the model could correctly simulate phenology, leaf area, dry matter and grain yield during both, calibration and testing, under no-till and conventional systems, combined with tensiometer and class A pan irrigation scheduling methods. Conversely, the model did not show the same performance for soil moisture simulations.