Progress report for GS23-292
Project Information
Dairy production in Texas is one of the fastest growing agricultural sectors, with billions of gallons being produced and sold each year. However, with the production of useable milk comes an increase of milk not fit for human consumption, or “waste” milk. Previous studies have shown that a mixture of waste milk and water can act as a fertilizer, causing rapid growth and more available protein in plants. In addition to this, the milk solution can mitigate soil acidity, acting as both a fertilizer and a lime. In the Texas High Plains, many counties are leading dairy producers but also comprise a large proportion of the state’s acreage enrolled in the Conservation Reserve Program. Additionally, many counties in the Texas High Plains are among the leading producers of annual forage crops such as wheat and sorghum in the state. This study intends to assess the effects of land application of milk on vegetative cover, yield, species composition, and nutritive value of native pastures; yield and forage nutritive value of annual forage species; soil health; and ecosystem services. Vegetative measurements will include collection of vegetative cover and composition data along transects and clippings to monitor biomass production and forage nutritive value. Soil health will be measured in form of pH, bulk density, carbon sequestration, and microbial activity via CO2 evolution. Four waste milk application rates (0, 10, 20, and 40 lbs of N per acre) will be applied in controlled greenhouse settings and in field settings.
The objectives for this research are to evaluate how various application rates of milk (0, 10, 20, and 40 lbs of N/acre) will influence:
- species composition and yield of native pastures
- yield of annual forage species
- forage quality through alterations to protein and digestibility
- soil health parameters (e.g., pH, microbial activity, respiration, and carbon sequestration)
Research
Greenhouse trials:
Greenhouse trials will involve waste milk application to individual wheat and forage sorghum plants grown in 1-gal grow bags. Milk will be applied in appropriate volumes to provide N rates equivalent 0, 10, 20, and 40 lbs of N/ac. In each species trial, 18 pots will be allocated to each of the four treatments. Prior to milk application, a subset of 6 pots per treatment will be destructively harvested to assess above and below ground biomass production. Following milk application, additional subsets of pots will be harvested in the same manner at two time points to capture effects in different plant growth stages. Measurements will include assessments of above and below ground biomass and reproductive shoot production. Basic soil analyses will assess changes in soil nutrients over time after milk application. Soil C fluxes will be evaluated using an in vitro procedure and will provide information about the effects of milk application on microbial activity.
Wheat plants grown in a greenhouse at Texas Tech had milk treatments applied in March 2025. Baseline samples were collected to assess aboveground biomass and root production and forage nutritive value. A subsequent sampling will be completed in April 2025 to assess the effects of milk application. In April 2025, sorghum will be planted for the greenhouse pot study.
Field trials:
Plots will be established at a research facility owned by Texas Tech University. The site is dominated by native perennial grasses. Individual plots will be 0.06 ac. Waste milk will be collected or donated from a local dairy and will be applied in appropriate volumes to provide 0, 10, 20, and 40 lbs of N/ac. Treatments will be applied in a randomized complete block design with three blocks (12 plots total). Milk will be applied in late April - May 2025. Baseline vegetative sampling will occur prior to milk application. Post-treatment measurements will be made during June, August, and October 2025 to evaluate the effect each solution has on vegetation and soil during the growing season. Vegetative measurements will be taken every 3 m on one 15-m transect per plot. Cover percentage of species and vegetation classification will be evaluated and recorded for each frame, and vegetation will be clipped and placed into bags for drying and weighing later. Nutritive value will be determined on biomass samples by sending to an external laboratory for a basic nutritional profile, including crude protein, neutral detergent fiber, acid detergent fiber, ether extract, and total digestible nutrients.
Soil sampling will occur in a grid pattern evenly spaced within each plot, with multiple 6-inch cores being collected in total for each plot. Soil cores will be composited in a five-gallon bucket, then placed into bags for drying. Composited samples will be ground using mortar and pestle, then a sieve will be used to sift out any organic material greater than 2 mm in size. A small amount of each sample will be combined with DI water and tested for pH for each plot. Microbial activity will be tested by fumigating 12 grams of each sample for 24 hours, then testing using potassium chloride method with a spectrophotometer. Remaining soil samples will be sent to an external laboratory for a general soil test. Soil samples will be taken prior to milk application, one-month post-application, and at the end of the growing season.
We have no results yet from our greenhouse and field trials. In the greenhouse trial, baseline wheat samples were collected prior to milk application in March 2025.
Educational & Outreach Activities
Participation Summary:
We have not yet conducted any education or outreach activities.
Project Outcomes
We have no outcomes to report at this time.
We have no recommendations to report at this time.