Achim Dobermann, deputy director general for research at the International Rice Research Institute (IRRI; http://irri.org ), and Leigh Vial, head of IRRI's experiment station, conducted a special project, the IRRI Agronomy Challenge, in which they demonstrated how to grow a productive rice crop in a 25 x 100-meter field on IRRI's research farm. In this installment, they wrap up the project with some keen insights.
Commentary from Achim:
June 22. Today, we sat down in the coffee shop to evaluate what we accomplished. There is nothing better than doing a bit of self-critical learning. Remember, we set out to grow a rice crop with a yield goal of 7 t/ha, and we had hoped that by applying best management practices we'd achieve that with good efficiency of critical inputs, and thus also turn in a decent profit. So, we looked at yield gaps and we produced a simple crop budget sheet.
Let's look at yield first. We came out at 5.24 t/ha rice (paddy at 14% moisture) in the bin, so why didn't we achieve 7 t/ha? There were three major reasons (types of yield gaps):
• Bad weather. To assess that, we ran a crop growth simulation of the theoretical yield potential of rice for the actual weather encountered in our dry season, and for each of the 20 years before (1992-2012). We used the ORYZA2000 model which assumes no growth limitations or yield losses by water, nutrients or pests. It simulates the ideal crop, a theoretical maximum one can only get with perfect management. The simulated long-term average yield potential was 10.6 t/ha with the model settings chosen, but it was only 8.7 t/ha in our cropping season.
• Grain losses due to lodging/combine harvest. We lost at least 0.6 t/ha grain during harvest, when the crop had heavily lodged and we were not able to adjust the combine enough to avoid major shattering losses.
• Yield losses due to variable crop establishment and pests. We don't think that we were short of nutrients or water at any point during the crop cycle, but we struggled with getting an even crop stand (had to re-seed and even re-plant in some areas).
Leigh came up with a basic crop budget sheet, including the income generated from selling the paddy US$ 1747/ha) vs. all our expenses (US$ 1412/ha). Purists may argue that we should have applied our real salaries to calculating the labor costs, but let's just assume that we wanted to be like normal rice farmers and should use what they would pay for labor.
All in all, it was a great learning experience. Get out there and try it yourself.
International Rice Research Institute
6 years ago