This project will measure the impact of multiple cover crops on yields of subsequent crops and use partial budget analysis to evaluate the economic impact. We will expand our current learning circle for peer to peer education, results dissemination and cover crop promotion, resulting in increased knowledge and adoption.
- Document/ demonstrate the economic impact of cover cropping.
- Expand our peer to peer learning circle to facilitate transfer of cover crop information and expertise.
Strip-trials we established at 6 sites during summer/ fall of 2016 and 2017 for response trials in 2017 and 2018. Strips contained paired comparisons of with and without cover crop using the cooperators cover crop of choice. In 2016, two sites used winter rye following soybean, two used winter rye following corn grain and two following winter wheat, frost seeded red clover and a summer mix following wheat harvest. In 2017, two sites used rye after corn, one used rye after soybean and three used red clover with wheat. Site characteristics and dates can be found in table 1. All sites have long no-till histories and trials were replicated 3 to 5 times. Cooperators followed their routine field practices for establishing and terminating the cover crop. In the wheat trials, clover was terminated in October, the majority of the summer mix winterkilled although a few species required chemical termination in spring. Winter rye was terminated in spring. Aboveground biomass was sampled before termination and analyzed for dry matter (DM), nitrogen (N) and carbon (C content).
Corn or soybean were grown using the cooperators routine production practices and yield was measured from the center six rows of each strip using a weigh wagon. Grain moisture was measured, and yield adjusted to the appropriate moisture.
Data was subject to analysis of variance procedures to determine if significant treatment differences occurred. Sites were analyzed separately.
Partial budget analysis, which accounts for cost and return differences between systems was used to calculate a net return per acre. The analysis included additional costs for cover establishment, management and interest (constant costs) and costs associated with additional corn yield including drying, hauling and nutrient removal (yield-dependent costs). Returns include additional corn yield and the value of the N credit (if applicable). Actual market prices were used in the analysis. Cooperators maintained records of inputs used with prices as well as additional field operations. Additional field operations (drilling and clipping) associated with cover crop use were charged using published custom rate guides. Grain hauling and drying charges were standardized and based on custom rate guides (hauling, $0.13/ wet bu.) or local market charges (drying, $0.047/ point moisture) using harvest moisture. Interest was calculated at 5% APR from the time of cover crop establishment to corn harvest. This also included additional field operations for cover crop management. Nutrient removal costs (P and K) were based on University of Wisconsin-Extension coefficients and actual prices paid by cooperators for nutrients applied for the 2017 growing season (P as diammonium phosphate, K as potash). Corn price was determined for the site fields based on forward contract or local spot price on the day plots were harvested. Breakeven yield response and corn price were calculated once a net return per acre was determined.
Cover crops in wheat systems (cases 1, 6 and 8) were more productive in terms of biomass yield than systems using winter rye (Table 1) which was expected given the longer growing period available. Carbon to N ratios were sufficiently low that residue should not tie-up N and affect corn yield.
Corn responded positively to previous cover at 4 of the 6 sites and negatively at 2 (Table 2). Positive responses ranged from 2.8 to 5.3%, negative from 0.1 to 0.5%, however yield differences were not significant at the 5% level of probability. In general, corn yields were very high for all the sites, especially given the well-drained nature of the soil types.
Cover crop use created a negative return at 5 of the 6 sites, ranging from -$4.12 to -$59.3/ acre (Table 3) despite positive gross returns at 4 of 6 sites ranging from $20.06 to $33.60/ acre. Of the sites with the largest losses, 2 (sites 3 and 6) had a yield loss, site 1 used an expensive cover crop mix and site 6 had both yield loss, expensive cover crop and no N credit. Site 1 had the highest corn price which could not overcome cover crop cost, emphasizing the need for minimizing cover crop cost.
Sensitivity analysis used to determine breakeven yield response and corn prices. Breakeven yield response under market conditions encountered are modest (Table 4) compared with corn price. Five of the sites would have required increases from 4.1 to 6.3% which should be obtainable with management. Site 6 would have required an 11.3 increase which is due to the lowest corn price and the most expensive cover crop system with a clipping operation and additional herbicide required for termination. Where yield responses were positive, corn prices exceeding $4 /bu. are necessary all other things being equal (Table 5). For Site 1 with the expensive cover crop mix and modest yield response, breakeven corn price is $7.67/ bu. which will probably not be obtainable in the near future. This further underscores the need to achieve yield increase and minimize cover crop costs.
Crop yield was increased by cover crop use in the 4 trials with usable data (1 site was damaged by deer, another had no control because the cooperator planted a different cover crop in the fallow strips) and yield responses were statistically significant at 2 sites (Table 6).
Partial budget analysis indicates that yield increase only produced a positive return in one case which interestingly, used the most expensive cover crop which produced an 8.7% yield increase (Table 6). Combining years, corn had a 3.2% average yield increase, soybean 1.9%. Averaged over crops, we’ve experienced a 2.9% yield increase (Table 7). Sensitivity analysis indicates a 5.4% increase is needed to break even. The cooperators are quick to point out that even though yield increases are not always enough to create a positive net return, it reduces cover crop cost (Table 8). As a group, we have an average actual cost of $31.23/acre, but the average net cost is $13.70/acre.
Trials will be repeated in 2019 and we will initiate our outreach work.
Educational & Outreach Activities
Outreach work in 2017 included just our immediate learning circle looking at plots. Formal outreach begins in 2018.
Cover crops can increase crop yield, we need to learn how to increase it to make the practice profitable.
One year of research data.
We will being work towards measurable outcomes in 2018.