Abstract
The cropping system model, namely, the crop environment resource synthesis-rice (CSM-CERES-Rice) model, is a decision supporting tool for the design of crop management. This study aimed to determine management practices for increasing rice (Oryza sativa L.) production in Laos by using the CSM-CERES-Rice model. The model was evaluated with data sets from the TDK8 and TDK11 cultivars in farmers’ fields in the Vientiane plain in 2012. Anthesis and harvesting dates, growth and yield for various management scenario combinations (eight transplanting dates × two levels of plant densities × three rates of nitrogen (N) fertilizer application) for both cultivars were simulated by the model from 1980 to 2012. The model evaluation results showed strong agreement between simulated and observed data for days to harvest with a difference within four days. The model provided acceptable accuracy for grain yields with normalized root mean square error values ranging between 1 and 16 %. The results from the model application indicated that TDK8 and TDK11 produced similar yields. Transplanting TDK8 with two plant densities produced similar yields. The highest yield for both cultivars was achieved on the transplanting date of 15 Jan. N-fertilizer application at 60 and 120 kg N ha−1 was able to increase yield for TDK8 by 50 and 87 %, respectively, and for TDK11 by 54 and 70 %, respectively. Rice transplanted on 15 Jan with 5 seedlings hill−1 and N-fertilizer at 120 kg N ha−1 had the highest average yield for both cultivars with 6,460 and 6,351 kg ha−1 for TDK8 and TDK11, respectively. The CSM-CERES-Rice model is an alternative tool in determining crop management practices for rice production.
Highlights
Rice (Oryza sativa L.) is the most important food for half of the world’s population especially in Asia (Schiller et al, 2006)
The greatest difference (-4 days) was found for TDK8 grown on 13 June 2013 with N-fertilizer at a rate of 80 kg N ha−1 followed by -3 days for TDK11 grown on 10 July 2011 with N-fertilizer at a rate of 73 kg N ha−1
The results for simulated data showed that TDK8 flowered at 83 days after transplanting (DAT) and had 122 days to harvest, whereas TDK11 bloomed at 76 DAT and could be harvested at 108 days
Summary
Rice (Oryza sativa L.) is the most important food for half of the world’s population especially in Asia (Schiller et al, 2006). In Laos, rice is mostly cultivated in the plain areas which account for more than 80 % of the agricultural areas of the country. Records from the Office of Agricultural Statistics of Laos indicate that the average rice yield is lower than the expected yield level of 2.5 t ha−1. There are several factors that impact rice production, including management practices such as cultivar use, transplanting date, plant density, fertilizer application, irrigation amongst others. Identification of suitable crop management practices could provide information for designing a plan to increase the rice yield of this production area. This process is time consuming and expensive as many years of experimental trials are required. Cropping systems are extremely complex and many factors have to be considered to achieve long-term sustainability (Geng et al, 1990) in major rice growing areas
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