Tag Archives: Phosphorus

Feeding Hay to Improve Your Land – Part 6

Feeding Hay to Improve Your Land – Part 6

By   /  April 1, 2019  /  1 Comment

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This is the last part in Jim’s series. If you missed any part, here are links to catch up: Part 1,Part 2Part 3Part 4 and Part 5.

Hay is more Carbon (C) by dry weight than anything else. When we feed hay we are also adding carbon to the soil in addition to the Nitrogen (N) and Phosphorous (P) discussed in the earlier posts in this series. Adding carbon increases the water and nutrient holding capacity of the soil through increase in soil organic matter.

How much carbon do we add to the soil with hay feeding?

Let’s do the math.

Hay is typically between 40-50% Carbon depending on plant maturity at harvest time. Some of this C is in cells as soluble sugar or other easily digested materials. The bulk of the C is in plant fiber that varies in degree of digestibility.

What’s left behind after feeding is a combination of unconsumed plant material and dung and urine. Both are important contributors to soil health.

Unconsumed hay is intact plant material that helps provide the ‘armor’ on the soil. During the growing season we refer to litter cover on the soil surface. Hay residue provides the same benefits to the water cycle as plant litter.

The consumed part of hay that is not digested comes out as manure. We have already discussed the N & P values of manure and urine following hay feeding. Whereas we can add too much N or P to the soil through excessive hay feeding, it is almost impossible to add too much C.

The digestible part of the hay is utilized by ruminant livestock as their primary energy source. Maintenance quality cow hay may be as low as 50% digestibility while high quality ‘calf hay’ may be close to 70% digestible. The C from digested material is incorporated into body tissue or expelled as CO2.

It is the non-digested plant material that contributes to building soil organic matter through dung returned to the soil. Manure on the ground does not contribute a lot to ‘soil armor’, but it contributes to feeding soil life.

The rate of manure breakdown is largely driven by digestibility of the residual fiber. If rumen microbes could not quickly digest it, soil microbes aren’t much faster. Manure breaks down much more quickly in warm-wet environments compared to cold-dry environments.

Hay residue left on the ground will ultimately contribute to soil organic matter. Many people have the bad habit of wanting to burn residue piles in the Spring. Please, do not!

These piles become enriched soil organic matter sites and can be above average production areas for years to come. Burning piles sends most of the valuable C into the atmosphere.

While in the first year following feeding there may be some weeds grow up on these piles, most of those weeds are making a contribution to soil development or get grazed by the livestock during the growing season.

The bottom line is, each ton of hay fed will contribute about 400 to 600 lbs of C to the soil as either hay residue or manure.

That is a valuable addition to your land. Make the most of it!

 

This is the last part in Jim’s series. If you missed any part, here are links to catch up: Part 1, Part 2Part 3Part 4, and Part 5.

 

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Feeding Hay to Improve Your Land – Part 5

Part 5 of Jim Gerrish article on Feeding Hay to Improve Your Land.  American Grazinglands Services. 

Find Part 1, Part 2, Part 3, Part 4.

Reprinted from On Pasture.

By   /  March 25, 2019  /  2 Comments

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In case you missed them, here are links for previous articles in this series: Part 1, Part 2Part 3, and Part 4.

We have so far only considered the role of buying and feeding hay as a Nitrogen source for your pastures. Hay is also a great source for slow-release Phosphorus to benefit your pastures.

Manufactured P fertilizers have recently been shown to be detrimental to the presence and function of beneficial mycorrhizal fungi in the soil. Using fed hay as a P source rather than concentrated soluble fertilizers feeds the fungi rather than diminishing them.

Factors Limiting Plant Growth

Nitrogen is generally considered to be the first most limiting nutrient for plant growth in terrestrial environments. Phosphorus is very often the 2nd most limiting nutrient. Unlike the N fixation process carried out by legumes in association with Rhizobia bacteria, we cannot create P out of thin air.

P is critical to both plants and animals as all energy transfers within plant and animal are mediated by P containing compounds. Abundant P is necessary to have healthy pastures and livestock.

Almost all P excreted by animals is in the dung. Because most cattle defecations occur when the animal is at rest, dung tends to accumulate where animals congregate – on the feeding line for example, or where cattle bed in hay not consumed. It does not get spread out over the entire pasture area if feeding is limited to small areas of the pasture.

This why spreading the hay out in the feeding process helps the P cycle.

Excess Nutrients Cause Problems

While P is a critical component of life, it also has pollution potential if we are allowing manure to concentrate in areas prone to surface runoff and soil erosion.

Mismanaged hay feeding can lead to excessive runoff of fecal material into surface water leading to aquatic weed growth and algal blooms. The ‘dead zone’ in the Gulf of Mexico and Chesapeake Bay are due to P runoff as well as N runoff.

How Much P Does Hay Feeding Provide?

Using our previous example of bale grazing with over 20 tons of hay/acre fed, the P load would be about 80 lbs/acre. That is not an excessive amount of P, although the N load was quite high.

Since that P is almost all contained in dung pats, it is slowly released back to the soil through microbial decomposition processes. The greater the biological and insect activity in the soil, the quicker the release process.

We only have a possibility of P contamination of surface waters when there is actual water runoff and/or soil erosion taking fecal particles and soil to the riparian areas.

The key to minimizing risk of P pollution from hay feeding is keeping the feeding areas well away from surface water.

Let’s keep them high & dry!

Buying Hay

 

Finding NPK in forage via test results

Given the retail prices of N, P, and K – (Nitrogen, Phosphorus, and Potassium) from Butterfield Grain Associates in Meadville, MO.

Nitrogen – 3.71 lbs times .42/lb = $1.56

Phosphorus – 1.63 lbs times .35/lb = $0.57

Potassium – 8.875 lbs times .29/lb = $2.57

Total NPK value  = $4.70 per 1250 lb hay bale or $12.17 per ton.

This value doesn’t include micronutrients and the organic matter in manure and wasted hay, including calcium, magnesium, etc.

Purchased bales of mature warm season grasses weigh about 1250 lbs each.  I sent core samples to Ward Laboratories to have analysed for feed value as well as fertilizer value.  Here are the results:

Ward Labs - Libby hay Sep 2017