Testing N efficient, high methionine corn hybrids with organic farmers

View the project final report

Commodities

• Agronomic: corn

Practices

• Animal Production: feed/forage, feed rations
• Crop Production: crop improvement and selection, food product quality/safety, nutrient management, organic fertilizers, plant breeding and genetics, tissue analysis, Nitrogen efficient/nitrogen fixing corn
• Education and Training: demonstration, extension, networking, on-farm/ranch research, participatory research
• Energy: energy conservation/efficiency
• Farm Business Management: budgets/cost and returns, value added
• Natural Resources/Environment: nitrogen efficiency and prevention of pollution from fertilizers
• Production Systems: dryland farming, organic agriculture, transitioning to organic
• Soil Management: increasing nitrogen efficiency of crops

Corn is North America’s most productive and most grown cereal.  But it has pollution problems due to the necessity for large amounts of nitrogen fertilizers and problems with a lack of nutritional density in its grain.   This research project focused on testing new hybrids bred at the Mandaamin Institute which have potential for resolving both of these problems.  These hybrids possess microbial partnerships that enable the corn to efficiently take up minerals and nitrogen without the use of fertilizers.  The hybrids were studied in the context of different farming systems and soil fertility conditions.  Studies with microscopy, field trials on different farms, and mineral and natural isotope analyses showed that 1) the plants exercise rhizophagic cycles with seed associated bacteria, leading to nitrogen efficiency in field trials, high levels of δ¹⁵N in tissues, and grain with high protein and mineral contents; 2) these partnerships result in comparable yields to manured commercial hybrids where no manure is added to the Mandaamin hybrids; 3) Hybrids with the Mandaamin inbred C4-6 as a parent particularly express these traits and also appear to fix N₂.  4) The C4-6 based Mandaamin hybrids also respond negatively to fresh manure but positively to high organic N and to high soil protein levels resulting from cattle manure.  5) The negative effect of fresh manure applications on the C4-6 based hybrids extends to yield and mineral uptake and this problem is worse on soils with low organic matter content. 6)  The Mandaamin hybrids have grain with a high nutritional value due to their high content of the essential amino acids methionine and lysine and their enhanced mineral content and this may offset a slightly lower yield.  Future research should be directed towards testing and confirming concepts developed in the course of this project while extending the testing to more farms.  Breeding should be fostered that focusses on stability for both microbial assisted processes of rhizophagy and N₂ fixation coupled with adequate yield performance and enhanced nutritional value under variable soil conditions with reduced N inputs.

Corn is the major cereal crop for North America and the most productive cereal in the world.  However, conventional corn production is largely dependent on the use of mineral nitrogen fertilizers.  Organic farmers often depend on bought in chicken manure.  Nitrate production in the soil under corn, coupled with the use of these N fertilizers results in surplus nitrate in the soil.  This nitrate is denitrified by bacteria to produce nitrous oxide, a potent greenhouse gas.  The excess nitrate not used by the crop leaches from the soil and causes massive pollution of wells, lakes, rivers, and also the Dead Zone off the Gulf of Mexico.  Modern hybrids have been found to have an enhanced ability to foster microbes in their rhizospheres that increase nitrification in the soil and denitrification (Favela et al., 2021).  

Furthermore, the-sided focus on increased yields may have reduced nutrient density of crops and thereby affect the health of end users.

This project was about evaluating the impacts and value of new, experimental hybrids which have been developed to reduce the need for nitrogen fertilizers while increasing nutrient density.  These hybrids were developed at the Mandaamin Institute, mostly under organic farming conditions that were N limited.  They resulted from a field based breeding program (Goldstein et al. 2012; 2019) that, up to now, has utilized 51 growing seasons in Wisconsin, Chile, Puerto Rico, and Hawaii.  The program selected corn for the needs of organic farming including for better nutritional value and nitrogen efficiency. The hybrids that resulted may have potential for resolving some of the Midwest’s most intractable problems with corn and N pollution that go beyond organic farming.  This possibility is due to partnerships with microbes (Goldstein, 2016). 

During this project the impacts and value of the Mandaamin hybrids were evaluated using on-farm testing.  Objectives included 1) testing several Mandaamin hybrids on multiple farms to determine their agronomic and quality characteristics and effects of soil and soil management; 2) examining nutrient uptake, nitrogen efficiency and nitrogen fixation in the hybrids; 3) testing whether inoculating seed with N₂ fixing bacteria would improve crop performance and N efficiency.

We used replicated trials and soil analyses to estimate yield, quality, and N efficiency of the Mandaamin hybrids on different farms.  Manure trials were utilized, and bacterial inoculation was added as an extra test factor because it seemed increasing relevant to the matters at hand.  In the descriptions below, these trials are referred to as the SARE manure/inoculation trials. 

In the course of the project, events caused changes from the initial plan.  Extensive soil and plant sampling and analyses that had been planned for 2018 proved not to be possible due to illness contracted by one of the two Mandaamin Institute technicians and illness by the principal investigator at the end of that growing season.  Furthermore, additional sites and plots that had not been planned in the initial proposal became available in 2019 due to funding of an OREI project together with the University of Illinois.  This OREI project involved un-replicated strip plots comparing multiple Mandaamin hybrids with commercial checks on different farms.  These experiments are referred to as the varietal trials.  A decision was made together with regional SARE leadership to incorporate those extra sites, to use SARE funds to better monitor these sites with soil and tissue testing, to modify the approach to the research accordingly, and to include a conventional farm into the plan.  As will be shown below, pursuance of these varietal trials with SARE funds proved to be highly rewarding from the standpoint of gaining information.

Furthermore, to compensate for the first year, efforts were carried out in 2021 that included limited trials to clarify questions raised by results in preceding years and to analyze data from the overall effort.

The data gathered by the project was substantial.  More analyses of the data in this report and other data are planned to further harvest pertinent results into the form of publishable papers.  So this report should be regarded by the reader as preliminary information which will probably be modified in the review process.  In this report we focus on the most important findings and there are a few experiments not reported on because their results were not essential to the overall findings.  Aside from that, the ample tables and graphs used to describe the results have resulted in a large report.  So in order to focus the reader on the outcomes of the project, rather than burying them first under voluminous tables,  we will present our summary and discussion section first, then lead into the context and background sections followed by methods, description of results, and citations.