The links between nitrogen fertilizer rates and varying crop rotation schemes are examined in this project. The role that organic matter inputs play in supporting corn-soybean rotations also was investigated.

From 2009-2012 the COBS team used a standard method to estimate carbohydrates in the biomass harvested from the biofuel systems in order to determine the cellulosic yields. This project performed the same analysis for 2012 harvested biomass, and further analyzed biomass from 2009-2012 using a method that is less commonly used due to its expense, but is much more accurate.

This trifold brochure explains the Sustainable Agricultural Land Tenure (SALT) Initiative, a collaboration of the Drake Agricultural Law Center and the Leopold Center. A number of resources have been created as part of this initiative including The Landowner's Guide to Sustainable Farm Leasing, The Landowner's Decision Tool, videos, podcasts, sample leases and other organizations.

Work continues in Year 16 of a long-term experiment comparing organic and conventional crop rotations. Adverse weather conditions in 2013 affected the production and performance of several crops in the rotations being studied. As a consequence of extended wet weather in spring, poor stands, delayed weed management and subsequent high weed populations, organic soybean yields were 26 percent lower than 2012. Organic corn yields were, however, greater than conventional corn, even when re-planting occurred on June 8.

This was the original project description: This is an expansion of a previous Leopold Center competitive grant (M2009-23), which supported the development of a basic semi-automated mechanical intra-row weed removal system for vegetable crops. The investigators will conduct field trials to evaluate and improve the prototype.

This study provided the first Iowa assessment of the availability of beef cattle manure phosphorus (P) for crops since the early 1970s.

Winter canola shows promise as an addition to crop rotations in Iowa. This project determined optimal seeding dates for this cover crop and explored practices to enhance production. It was estimated that the latest Iowa seeding date varies from around August 31 in the north to September 12 in the southeast.