Mathematical models of water application for a variable rate irrigating hill-seeder

Authors: YANG, SHUMING - Northwest Agriculture And Forestry University; YANG, QING - Northwest Agriculture And Forestry University; Yang, Chenghai

Submitted to: Asian Conference on Precision Agriculture
Publication Type: Proceedings
Publication Acceptance Date: 11/30/2009
Publication Date: 12/28/2009
Citation: Yang, S., Yang, Q., Yang, C. 2009. Mathematical models of water application for a variable rate irrigating hill-seeder. Asian Conference on Precision Agriculture. CDROM.

Interpretive Summary: A variable rate irrigating hill-seeder can adjust water application at planting automatically according to the difference in soil moisture content in the field to alleviate drought and save water. This study developed mathematical models for determining minimum application water and for delivering the predicted water amount for a variable rate irrigating hill-seeder. Laboratory and field tests showed that these models correctly predicted the minimum amount water required for each area and accurately controlled the delivering system to apply the right amount of water. These results indicate that the variable rate irrigating hill-seeder in conjunction with the models can be used for variable rate irrigation at planting.

Technical Abstract: A variable rate irrigating hill-seeder can adjust water application automatically according to the difference in soil moisture content in the field to alleviate drought and save water. Two key problems to realize variable rate water application are how to determine the right amount of water for the corn seed to germinate and how to control the electromagnetic valve to supply the predicted water amount. In this study, mathematical models for determining minimum application water and models for electromagnetic valve control time were developed. A static experiment was conducted using a self-developed variable rate irrigating hill-seeder. Different amounts of water ejected from the electromagnetic valve were measured by changing the water level in the tank and irrigating time. The mathematical models for electromagnetic valve control time were established based on the relations among water amount in tank, irrigating time and water amount supplied using linear regression and artificial neural networks. Regression results showed that the adjusted coefficients of determination for the linear regression models were 0.992, 0.991 and 0.998 when the tank was 100% full, 1/2 full and 1/8 full, respectively. A 2-5-1 artificial neural network was used to predict irrigating time. The network provided high prediction accuracy with a maximum deviation of 3.95 ms and an average deviation of 1.46 ms. These results indicate that the variable rate irrigating hill-seeder meets the design requirements and can be used for variable rate irrigation at planting.