Goal: to assess the individual and interactive effects of planting date and maturity rating on soybean yield potential across MN
In Minnesota, soybeans maintain most of their yield potential when planted up until mid-May. After this point, decreases in yield potential become more significant. However, on average across the past 5 years, barely half of the state's soybean acreage has been planted before the end of this optimum time window. Moreover, on average, ~20% of the acreage was planted during June. Extreme situations in 2019 and 2022, when half of MN soybeans were planted in June, affected these values. Delays in planting are associated with weather conditions that are difficult to predict. On the other hand, responses to the landscape or agricultural practices such as drainage, no-till systems, cover crops, or weed control may be more predictable.

How much total production are we losing due to planting delays? What is the value to individual farmers for earlier planting?

We can try to answer this question by combining the reported planting progress (USDA) with information that relates planting date and yield loss (UMN.Extension). Across the last 5 years MN would have lost up to 7% (26 M bu/yr) of its potential soybean production because of delayed planting; this loss could climb to 14% (73,8 M bu) for springs like 2022. Thus, it seems that a considerable proportion of the soybean production across the state is being lost because of planting delays, costing Minnesota producers hundreds of thousands of dollars annually.

The yield loss prediction that we have described above is based on a limited number of experiments (years and locations) which makes it difficult to extrapolate findings to the entire state, let alone incorporate a measurement of probability or risk to the analysis. Crop models have proven to be useful tools to solve these limitations. Crop models can extend yield predictions in space and time by accounting for the effect of the environment (site, planting date) and the cultivar.

Meanwhile, current guidelines for managing delayed or replanted soybeans indicate that farmers should not adjust soybean maturities until June 10th. The basis for this delayed action is that lower yield potentials of shorter varieties would not compensate for their better fit to the remaining cropping season. However, there has been a great advancement in genetics for early-maturing varieties (Kadel, 2022).

Can an earlier shift to short maturity with modern varieties attenuate the yield loss resulting from planting delay? At what date should producers shift to shorter maturities, and what reduction in maturity rating is more appropriate for the various regions of MN?

We propose to evaluate different maturity rating and planting date combinations in controlled field experiments using recently-released and high-yielding varieties in combination with a calibrated crop simulation model to extend the predictions to the main soybean cropping area of MN. This information is not currently available, and it will provide further insight on location- specific management across soybean cropland of the state.

i) Redefine the impact of the delay in planting date and the maturity rating on soybean yield potential using current elite cultivars.
ii) Generate local estimations of the impact of planting delay on potential yield of soybean across MN.
iii) Generate local guidelines for the management of maturity rate according to the planting date delay across MN.

A tool to predict the effect of planting date delay (May-June) on potential yield (yield loss) for a transect of locations across MN (south-north).
A tool to assess the effectiveness of shifting cultivar maturity rates according to the planting date (May-June) for a transect of locations across MN (south-north)
After year-2, a digital tool (phone or ‘shiny’ app) to guide producers in planting date and maturity group choices based on calendar data and selected location.

Update:
? Four experiments were conducted in four locations across MN (Grand Rapids, Crookston, St. Paul, and Waseca.
? Samples were processed and data analysis is in an advanced stage.
? We were able to estimate the potential yield loss per day in delay in planting date.
? We were able to estimate the effect of the maturity rate on the yield potential. yield loss per day in delay in planting date.
? We are starting with the calibration and validation of the crop simulation models in order to extend these results to other field conditions.

(1) Provide the collective effect of planting date on MN soybean production.
(2) Provide measurement of local effects (growers-specific) of planting for updating planting date recommendations across MN.
(3) Quantify the expected yield loss of planting delays for different locations, including a risk component. This will be beneficial to predict expected yields and incorporate risk analysis into management decisions.
(4) Provide guidelines useful to reduce the yield loss due to planting delays by adjusting maturity rate. This project will allow us to generate science-based recommendations to Minnesota soybean growers with the goal of maximizing yield across different planting dates.
(5) This project will allow us to generate management tools and a benchmark for delayed planting dates that will be relevant in the evaluation of increased use of alternatives like cover crops and double crops