Advancing Intensive Management of Corn Systems in Minnesota (Rainfed)

This project is focused on high-yield continuous corn systems. The objectives are to determine:

1. The yield levels possible in Minnesota.
2. How far current production is from that which is possible.
3. How the performance of a management system that integrates current scientific knowledge compares to current farmer practices.
4. If current university recommendations are capable of attaining and maintaining yields at levels close to yield potential.

This experiment compares two management systems: 1) current farmer practice and 2) a high-yield system that is also environmentally responsible (ecological intensification). For each system, current university nutrient recommendations are compared to advanced nutrient management. The performance of each management system and nutrient intensity regime is evaluated with corn yield and nutrient uptake, nitrogen use efficiency, soil residual nitrogen, soil fertility levels (macro- and micronutrients), and soil carbon. This experiment is a companion to the AFREC-funded high-yield irrigated continuous corn experiment established at Becker, MN in 2014. Results from these experiments will be combined with those from 19 other locations in 9 countries as part of an IPNI project, allowing the results from Minnesota to be placed in both U.S. and global contexts.
The goal of this project is to address the following questions that have been repeatedly asked by Minnesota farmers and the agribusinesses they support:

1. What yield levels are possible in Minnesota?
2. How far is current production from that which is possible?
3. Is our current scientific knowledge, when properly integrated, capable of creating marked improvements in system performance over current farmer practices?
4. Are current university nutrient recommendations capable of attaining and maintaining the high yields that are possible?

Four associated objectives are discussed below:

Objective 1: Determine yield levels that are possible in Minnesota.
Many farmers in the Corn Belt currently view 300 bu/acre as a high-yield target, but is this target appropriate for Minnesota? Evans and Fisher (1999) defined potential yield as, “…the yield of a cultivar when grown in environments to which it is adapted; with nutrients and water non-limiting; and with pests, diseases, weeds, lodging, and other stresses effectively controlled.” Potential yield therefore depends upon many management and environmental factors.

A crop growth model termed “Hybrid Maize” was developed by researchers at the University of Nebraska (Yang et al., 2004) to estimate potential yield at any given location and set of environmental conditions. The model estimates potential yield for two conditions: 1) when water is non-limiting, and 2) under rainfed conditions, using precipitation data from the location of interest.

Objective 2: Determine how far current production is from that which is possible.
Comparing the yields attained in this field experiment with those modeled by Hybrid Maize quantifies the gaps in yield that can potentially be exploited through management improvements.

Objective 3: Compare the performance of a management system that integrates current scientific knowledge to that of current farmer practices.
Past high-yield research in the Corn Belt focused on grain production as the primary metric of performance; however, society is now demanding other performance indicators such as nutrient use efficiency, nutrient cycling, and carbon sequestration. Ecological intensification, as defined by Cassman (1999), is a crop production system that satisfies the anticipated increase in food demand while meeting acceptable standards for environmental quality.

Unlike past high-yield efforts, ecological intensification focuses not only on crop production but also on profitability, sustainability, and creating a favorable biophysical and social environment. Local interdisciplinary teams of scientists who work with crop advisors and farmers have the expertise needed to integrate existing scientific knowledge to create crop production systems that have the greatest chances of meeting the multiple objectives of ecological intensification.

Objective 4: Determine if current university recommendations are capable of attaining and maintaining yields at levels close to yield potential.
Advanced nutrient management is a key component of ecological intensification. It must ensure that supplies of all crop nutrients, both macro- and micronutrients, are adequate to meet the demands of a high- yielding crop. Additionally, timing and placement of nutrients must be optimal for crop utilization throughout the entire season to create the greatest fertilizer use efficiency possible.
The International Plant Nutrition Institute (IPNI) is currently overseeing a multi-year, multi-country project. There are currently 19 sites located in the U.S. (3: Iowa, Indiana, and Virginia), Africa (2), Argentina (2), Brazil (2), China (2), Colombia (1), India (2), Mexico (4), and Russia (1). There is also an AFREC-funded high-yield irrigated continuous corn experiment that was established at Becker, MN in 2014 that is part of this network. The goal of this project is to compare farmer practice to ecological intensification and measure several performance indicators. Each of these treatments is a management system that is defined locally by small teams of university scientists who work with crop advisors and farmers.

It is intended that each experiment run 10 years at each location. Long-term research is required to allow sufficient time for measureable treatment differences in soil carbon to emerge and to assess annual variability in maximum yield level and the associated yield gaps. In each of the last 3 years, grant applications were submitted to the Minnesota Agricultural Fertilizer Research and Education Council requesting funding to establish a research site at Waseca, MN and to conduct this research for the first 4 cropping seasons. The council approved funding for the first 3 cropping seasons of this project. With this grant application, we request funding for 1 more cropping season, as a minimum of 4 cropping seasons are needed to meet the objectives of this project.

This experiment is located at the University of Minnesota Southern Research and Outreach Center at Waseca on a site with high yield potential, patterned subsurface tile drainage, and Nicollet clay loam soil. A continuous corn system is being used. Tillage includes stalk chopping and disk-ripping. The ecological intensification, farmer practice, and advanced nutrient management components of the management systems were developed following discussions with scientists, crop advisors, and farmers.

Methods for meeting Objective 1:
The Hybrid Maize simulation model will be run for both ecological intensification and farmer practice treatments using site, weather, and corn management data. IPNI has the developer of the Hybrid Maize model, Dr. Haishun Yang (http://agronomy.unl.edu/yang), on retainer to run the simulations and ensure 1) the integrity of the weather data being input into the model, and 2) the model’s customizable parameters are adjusted to local conditions and management practices.

Methods for meeting Objective 2:
Potential yield modeled by Hybrid Maize will be compared to the average yields of the ecological intensification and farmer practice treatments to determine yield gaps for both management systems.

Methods for meeting Objectives 3 and 4:
The main plot treatments for this study include:

1. Ecological intensification + current university nutrient recommendations
2. Ecological intensification + advanced nutrient management
3. Farmer practice + current university nutrient recommendations
4. Farmer practice + advanced nutrient management

For each main plot treatment, split plots are with and without nitrogen fertilizer, for a total of 8 experimental units per replication. There are 4 replications in the experiment.

IPNI has Dr. Hao Zhang (http://www.stat.purdue.edu/people/faculty/zhanghao/) on retainer. Dr. Zhang is a statistician with expertise in traditional, spatial, and time series statistics as well as weather data management. He is responsible for conducting statistical analyses across all sites and years of the project. He is also available to assist with statistical analyses at individual locations.

Statistical analysis will be conducted to test whether significant differences exist among the 4 main plot treatments. Comparing treatment 1 to 2 and treatment 3 to 4 determines if advanced nutrient management is an improvement over current university recommendations for both management systems (ecological intensification and farmer practice). The split plots (with and without nitrogen) will be used to calculate nitrogen use efficiency parameters for the 4 treatments.

The following variables will be statistically analyzed to determine the performance of the 4 main plot treatments:

Corn yield and nutrient uptake (all seasons): whole plant biomass yield and nutrient (total N, P, K, Ca, Mg, S, B, Cu, Fe, Mn, and Zn) uptake at growth stages V10 and R6 (physiological maturity). At R6, these measurements will be made for grain, cob, and stover fractions.

Corn nitrogen use efficiency (all seasons): partial factor productivity, agronomic efficiency, partial nutrient balance, and apparent crop recovery efficiency (Snyder and Bruulsema, 2007).

Residual soil nitrogen (after corn harvest in all seasons): extractable nitrate-nitrogen at 0-2, 2-4, 4-8, 8-12, 12-24, and 24-40 inches.

Soil chemical properties (after corn harvest in all seasons): soil pH, electrical conductivity, P, K, Ca, Mg, S, Na, CEC, B, Cu, Fe, Mn, and Zn at 0-2, 2-4, 4-8, 8-12, 12-24, and 24-40 inches.

Soil physical properties (after corn harvest in 2013 only): soil bulk density and particle size at 0-2, 2-4, 4-8, 8-12, 12-24, and 24-40 inches.

Soil carbon (after corn harvest in 2013 and at the end of this experiment): soil organic carbon, soil inorganic carbon, and particulate organic matter carbon at 0-2, 2-4, 4-8, 8-12, 12-24, and 24-40 inches were measured in the fall of 2013 and will be measured again at the end of this experiment to determine if carbon sequestration occurred. Since this experiment is intended to run 10 years and detectable differences in soil carbon are unlikely to occur during a short time period in the high organic matter soil at this site, the second set of soil carbon measurements will occur at the end of this experiment (around 2023).