Recipient Organization
UNIV OF MINNESOTA
(N/A)
ST PAUL,MN 55108
Performing Department
Soil, Water, and Climate
Non Technical Summary
Soil health management systems (SHMS), including reduced tillage and cover crops, are a key component of Minnesota's Nutrient Reduction Strategy, expected to reduce both N and P loadings by taking up excess nutrients, slowing and reducing surface runoff. In addition to these public benefits, experienced SHMS farmers claim that improved water infiltration and soil structure allow them more rapid field access after precipitation events, adding critical days of field work during busy spring and fall periods. These extra days not only provide agronomic benefits including timely planting and weed control, but relieve some of the intense stress of managing a complex operation on a tight timeline with unpredictable weather. This farmer claim has not been scientifically evaluated, despite its social and economic significance and potential to serve as a valuable outreach message to increase adoption of SHMS and manage water quality and quantity. Our objectives are to 1) assess the soil response to rainfall under different management systems (e.g., soil moisture and soil structure, such that soil may bear equipment despite high moisture levels); 2) estimate field working days and their economic impacts with SHMS and conventional systems; and 3) explore the importance of field working days for farmer quality of life and stress levels. These assessments will be integrated into outreach materials for the MN Office for Soil Health and partner organizations, with messaging designed to reach middle adopters who are not motivated by conservation alone.These objectives require a multi-disciplinary approach. To address Objective 1, the mechanism by which SHMS may improve field workability, we will evaluate soil moisture and soil aggregate stability before and after rainfall events to observe how changes in soil moisture status affect in both replicated research plots with different tillage and cover crop regimes. We will expand measurements to 6 on-farm sites in south-central MN, pairing 3 long-term SHMS systems with 3 conventional, full-width tillage sites, to evaluate maximum potential benefit. Dr. Lazarus will use the soil measurements to model field working days with and without SHMS, estimating economic benefit in Objective 2. Krekelberg will lead a survey of farmers in Objective 3, targeting some experienced SHMS farmers via membership in the MN Soil Health Coalition and the Sustainable Farming Association, and a more conventional population via statewide commodity group communication channels.
Animal Health Component
40%
Research Effort Categories
Basic
60%
Applied
40%
Developmental
0%
Goals / Objectives
Our objectives are to 1) asses the soil response to rainfall under soil health and conventional management systems; 2) estimate field working days and their economic impacts under soil health and conventional management systems; and 3) explore the importance of field working days for farmer quality of life and stress levels.
Project Methods
Objective 1: Assess soil response to rainfall under soil health and conventional management systemsMeasurements will occur over the 2021 and 2022 growing seasons at the Southern Research and Outreach Center (SROC) and 3 pairs of on-farm sites, each consisting of one long-term (>5 years) SHMS and one conventional farming system.To evaluate whether disturbance changes soil response to rain, each of the following measurements will be taken 24-36 hours before, 24-36 hours after, and 3-5 days after a rain event: soil moisture, sample for aggregates (collect ~2 c of soil to 6" with spade). Access tubes for Dynamax PR2 volumetric water content probes will be installed in each plot and farm field to monitor moisture to 1m with minimal disturbance. Penetrometer readings to 45 cm will be taken ~every 2 weeks using a FieldScout SC 900 Compaction Meter, alongside other measurements. In addition, a sample for surface bulk density will be taken at the outset of the experiment.These measurements will be performed during the spring season when planting, fertilizing and herbicide applications are likely (~April-June) and the fall harvest season for corn and soybean (~October). We will prioritize rain events >13mm for sampling, as these events are expected to fill soil pores with water and potentially destabilizing aggregates to the greatest extent.At SROC, measurements will be taken in a full factorial experiment with tillage (no-till, strip-till, and full-width rip/chisel plowing) and cover crop (no cover crop, cereal rye cover crop). Chisel plow and no-till regimes have been in place since 1984, strip-till was added in 2002, and cover crop treatments were established in 2018. These plots will represent the controlled application of one SHMS technique at time, allowing researchers to distinguish the effects of tillage and cover crop. A pilot study at SROC in spring 2020 suggested that rain events reduced penetration resistance, a measure of compaction, in a no-till cover cropped system, but not in a tilled no-cover crop system. In addition, the pilot study showed that without a cover crop, a no-till system was slightly wetter than other treatments, but treatments with cover crops were drier after spring rains, so we are confident that this measurement scheme, unique in its precipitation-specific timing, captures the phenomena of interest.To select farm locations, we will seek sites with at least five years' history of reduced tillage and cover crops, preferably both, in order to represent the maximum potential benefit of these systems. Conventional fields and cooperators will be located on the same soil map unit and landscape position to minimize edaphic variation. Within a field, map unit, and landscape position, a 10 x 10 m area will be selected to install moisture tubes and monitor for the season. Management data including tillage type and timing, cover and cash crop seeding rates and dates, nutrient management, and yields, will be collected for the two years of biophysical measurements.To characterize both SROC plots and on-farm sites, a set of 0-12" soil samples will be taken in the fall of 2021, post-harvest, to evaluate soil nutrient status, bulk density, and soil health (active and total soil C and N pools). A mini-disc infiltrometer will be used to estimate unsaturated hydraulic conductivity at least once over the course of the study, so that the measured responses to rainfall can be connected to a quick and accessible field measurement that conservation staff are likely to employ.Objective 2: Estimate field working days and their economic impacts with SHMS and conventional systemsDr. William Lazarus has created and tested a model using soil moisture status to predict days suitable for field operations based on 45 years of Lamberton, MN data on actual days suitable for fieldwork as recorded by SWROC staff. This model requires soil moisture estimates from days relevant to spring and fall field work. The 2019 pilot study suggested that moisture was reduced ~8% in no-till cover crop plots compared to tilled plots with no cover crop, leading to 3.9 more spring working days. Dr. Lazarus will perform similar calculations for each site, and estimate spring and fall working days under each management condition. These working days can be translated into an economic value based on the additional work that the relevant field equipment is able to perform in that time, or based on yield loss due to delayed planting in the spring (Coulter, 2018).Objective 3: Explore the importance of field working days for farmer quality of life and stress levels.A survey will be developed by Krekelberg, in consultation with WRC social scientist Dr. Adam Wilke, to evaluate farmer stress level during the peak spring and fall field work season. The survey will include questions on the number of days spent in the field, number of days prevented from field work by weather (specific to a given growing season), stress level, and overall quality of life. The survey will be pilot tested to ensure the questions accurately capture the data needed to inform the study. In order to ensure that we reach SHMS-focused farmers, we will distribute the survey via the MN Soil Health Coalition (~230 members) and the Sustainable Farming Association of MN (~970 members). In order to reach more conventionally-minded farmers, we will advertise with the MN Soybean Growers and through the MN Crop News list (over 2400 members). Grower commodity organizations have agreed to publicize the survey in their newsletter and social media, and a paper copy will be distributed to farmers at UMN Extension winter crop updates. Although responses will be anonymous, we will separate the data by region in order to explore regional differences in weather patterns. Data will be analyzed by a graduate student and Krekelberg, in consultation with Wilke, with results summarized and presented to local government conservation professionals as well as state and regional conference audiences, such as the Soil Management Summit, the SFA Soil Health Summit, the Minnesota Water Resources Conference, the Nutrient Management and Nitrogen Conferences, and the I-90 Cover Crop Tour. Results will also be shared with state agencies including the Board of Water and Soil Resources and MN Department of Agriculture.