1a.Objectives (from AD-416)
The overall objective of this project is to develop integrated crop simulators for resource management. The specific objectives include the development of modular simulators for major U.S. crops, and evaluation of environmental impacts of global climate change, water quality issues, sustainable agriculture, precision farming, etc. Research areas where knowledge gaps about plant and soil processes limit the accuracy of model predictions.

1b.Approach (from AD-416)
Develop a suite of process level crop simulation models for wheat, potatoes, corn, rice, peanut, cotton, and soybean; and integrate these with models for weeds, diseases, and insects. There are many crop models available; however to date there is no comprehensive crop management system developed for major crops grown in the United States. The selected crops are important to the U.S. economy; in addition they represent a wide range of plant types: C3 and C4, grain root and fiber, legume, and non-legume. From such a suite of models it should be possible to assemble modules capable of simulating many other crops with appropriate parameter changes and additional rate equations to fill up the gaps. The existing models for weeds, diseases, and insects will be further developed and integrated with crop models. In instances where mechanistic models to describe some processes do not exist, or are inadequate, new models of those processes will be developed. Where suitable data are not available, we will conduct experiments to generate needed data.

3.Progress Report
The corn model (MAIZSIM) and the soil model (2DSOIL) have been fully integrated. Water stress effects on growth and photosynthesis have been incorporated into the complete model (MAIZSIM). The model has also been modified to calculate nitrogen uptake by roots and account for nitrogen effects on growth and development. A detailed data set of corn growth, development and yield for several levels of nitrogen continues to be collected through field studies in Beltsville and on two grower's farms. The input and output data structures for the model have been implemented to be compatible with the Graphical User Interface for Crop Simulators (GUICS) allowing the model to be integrated with the interface. Process level information on individual leaf response to light, carbon dioxide, and temperature have been incorporated into the new potato model (SPUDSIM) to improve model's accuracy. Mathematical expressions for leaf appearance, duration, and expansion were incorporated with existing procedures for light attenuation and gas exchange Evaluation of model simulations versus independent growth chamber data indicate these changes are accurate. Data from experiments with nitrogen and water in potato in Washington State are being archived to use to validate the potato model. A uniformity study was carried out in the growth chambers to provide a baseline variability to provide a more robust statistical basis for comparison of treatments among the chambers.

4.Accomplishments
4a. Single most significant accomplishment during FY 2007:

A new mechanistic crop simulation model for corn (MAIZSIM) has been completed. There are no current simulation models for corn with comprehensive, two dimensional soil models that simulate the plant processes using current detailed, biologically based scientific knowledge on light interception, photosynthesis, and carbon partitioning. This corn simulation model will be an important management and assessment tool for agricultural managers, scientists, and policy makers. This accomplishment aligns with the NP 207 component to provide models, tools, and databases of science-based information and its effective retrieval, management, and analysis for agricultural management decision making.

4b Other significant accomplishments:

A potato model (SPUDSIM) was improved to more accurately simulate canopy light absorption and photosynthesis. The majority of existing potato models do not incorporate state-of-the-art advances in our knowledge of light attenuation and gas exchange processes within the canopy. However, the accuracy of model predictions can be improved by incorporating process level information on leaf gas exchange response to the light environment. Mathematical expressions for leaf appearance, duration, and expansion were incorporated into SPUDSIM along with procedures for simulating light attenuation and gas exchange. The modifications were tested against independent data. These additions improve the usefulness of the model for policy decision makers and growers to evaluate the effects of management decisions on potato production. This accomplishment aligns with the NP 207 component to provide models, tools, and databases of science-based information and its effective retrieval, management, and analysis for agricultural management decision making.

Interactive effects of nitrogen and carbon dioxide on potato photosynthesis and growth were quantified. Nitrogen management is a critical aspect of potato production, and the interaction of this nutrient, with other environmental factors, need to be quantified in order to improve crop growth assessment tools. Quantitative information on the effects of nitrogen with and without carbon dioxide enrichment was obtained from experiments and has been evaluated for use in the existing potato model SPUDSIM. This work contributes towards the development of a mechanistic potato model that will be a useful tool for management of potato and assessment of the effects of nitrogen and water application on yield and the environment. This accomplishment aligns with the NP 207 component to provide models, tools, and databases of science-based information and its effective retrieval, management, and analysis for agricultural management decision making.

5.Significant Activities that Support Special Target Populations
None

6.Technology Transfer

Number of non-peer reviewed presentations and proceedings

13

Review Publications
Timlin, D.J., Rahman, L., Baker, J.T., Reddy, V., Fleisher, D.H., Quebedeaux, B. 2006. Whole Plant Photosynthesis, Development and Carbon Partioning in Potato (Solanum tuberosum L.) as a Function of Temperature. Agronomy Journal. 98:1195-1203.