by Sanne Kure-Jensen
Better soils lead to better forage, improved animal health, higher milk quality and larger milk yield. “Soil fertility is the foundation to Integrated Livestock Cropping System [and] works to enhance the flow of nutrients within the biological system,” said Cynthia A. Daley, Ph.D., Organic Dairy Program Professor at California State University. Her goal is to improve pasture soil structure and biology. Daley’s research showed a clear economic benefit to amending soils for increased quality and quantity of milk in her dairy herd. She led a webinar hosted by eOrganic in late June. The webinar is posted at www.extension.org/pages/68131
Test soils and forage quality
Daley recommended farmers test pasture soils as the first step in developing and implementing an amendment and remediation program. Most state universities have soil labs. Soil tests will offer a baseline and recommendations. Forage quality reports will give fiber levels as well as digestibility, energy and mineral values.
Soil and pasture
For ideal pasture quality and forage yield, soils need a balance of macronutrients (Calcium, Phosphorus and Potassium) and micronutrients (Boron, Magnesium and Sulfur).
Ideal soil structure allows air, water and roots to penetrate into soils. Biological activity includes microbes, fungi, worms and insects. Plant roots take in nutrients and water while delivering energy/sugars and carbohydrates made through photosynthesis. Organic matter breaks down into humus, a stable source of slow release nutrients, which helps improve water retention.
There are many benefits to diverse soil biology:
Improved soil structure
Drought resistance – Improved water holding capacity
Degrading or tying up pollutants
Balanced micro and macro soil nutrients support ideal plant health, vigor and nutrition. Daley urged farmers “find a good Soils Coach.” She recommended a book called “Building soils for better crops – sustainable soil management” by Fred Magdoff and Harold van Es. This book is available free at www.sare.org/Learning-Center/Books/Building-Soils-for-Better-Crops-3rd-Edition. Daley also recommended “The Ideal Soil: A Handbook for the New Agriculture” by Michael Astera. This book is widely available online or at major bookstores.
Daley recommended farm managers seek ideal soil Cation Exchange Capacity (CEC) by ensuring optimal levels of Calcium, Magnesium, Potassium, Sodium and Hydrogen. Sandy soils typically have low CEC. High CEC is more common in soils with high organic matter and/or clay contents. High CEC soils will retain micronutrients (Sulfur, Boron and Molybdenum) better than low CEC soils. It will take more time and inputs to correct high CEC soils.
Ideal crop nutrition comes from soils with this balance: Calcium 75 percent, Magnesium 15 percent, Potassium 3.5 percent, Sodium 1 percent and Hydrogen 0 percent at a pH or 7.0. When Calcium levels are high relative to Magnesium, soils are ‘loose.’ With more Magnesium, soils are ‘tight.’ Be cautious with leachability of some minerals in sandy or low CEC soils.
Calcium — essential for uptake of many other nutrients, breaks up dense clay soils, improves air and water movement in soils, improves forage pectin levels, helps mobilize other minerals and help plants build greater root mass
Boron — helps translocate sugars, aids calcium absorption, root elongation and leaches easily in low CEC soils.
Sulfur — helps protein production, lignin digestibility and plant growth.
Worms and dung beetles
Earthworms feast on microbes. Their tunnels help water and air to move through soils. Phosphorus is seven times more available and plant usable in worm castings. Traditional fertilizers and animal fly treatments often kill dung beetles. Organic soil treatments allow the return of dung beetles. Their speedy processing and burial of cow plops reduces the fly and maggot populations improving cattle health.
Daley amended pasture soils per soil test recommendations each spring. Pastured were grazed intensively. Fences were moved every 12 hours. She prefers her animals graze quickly to avoid selective weeds. Forage species did not change during the year nor did the amended areas visually differ from the unamended areas.
Daley said, “It takes time to reverse five decades of traditional management.” The amended areas showed improved nutrient content. Forage samples were tested in spring, summer and late summer.
Daley’s fields have clay loam soils with high Magnesium, which need aeration. After amending and testing for several years, amended soils show rising Calcium levels and dropping Magnesium levels. All fields were overseeded each fall with a forage blend including white clover. Perennial rye comes back each fall when temperatures begin to fall.
Summer temperatures in Daley’s region require pasture irrigation each summer. Daley’s animals receive a mineral supplement on their parlor feed. Over time, farmers can reduce supplement feeding as forage quality continues to improve.
Nutritional levels and fiber digestibility shift as cool season grasses go dormant. Warm season grasses are typically less digestible. Forage during hot summers may need supplementing for ideal animal nutrition.
Daley reminded growers that the best way to grow and finish animals is to increase the energy and fiber content of grass and forage.
Forage is the cheapest feed. The animals collect it themselves reducing farmers’ labor and transportation costs of hay.
Improved soil mineral balance led to increased plant nutrition. This created forage with more vitamins and antioxidants, which improved animal health, milk quality and antioxidant levels. The amended soils generated about $200 more per dairy animal per season. Amendments cost slightly over $150 per animal. The amended fields offered extra forage yields saving $70 per animal in comparable feed (replacement hay).
Overall, the soil amendments were well worth their cost in materials and labor with returns well over $100 per animal.
Similar forage improvements will benefit the health and nutrition of beef cattle.
Daley shared her wish that milk from enhanced, balanced fields could be marketed as having improved nutrition. Even though that is unlikely in her region, soil improvements were more than economically justified. Her input expenses returned significant increased milk production.
Balanced soils often have higher organic matter levels and improved water holding capacity. Good soil biology leads to good aeration and deeper plant roots. These factors help protect pastures from extended drought conditions.
by Sanne Kure-Jensen