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The Value of Manure

Manure can be a valuable tool in berry crop production. It adds nutrients and micronutrients. Manure applications can increase or stablilze soil pH, increase organic matter content and improve soil structure. Indirectly, the addition of manure into a berry crop rotation can improve yields by improving soil moisture holding capacity, and soil structure.

There can be some down sides to manure application as well. Manure is sometimes considered a risk and a bother because of the hauling, the spreading, application timing and the question of when and how much nitrogen will be released. Applied improperly, manure can cause environmental contamination. Manure can be a source of pathogenic microbes, and if used too close to harvest, can increase food safety risks. Growers should follow best management practices for manure application to minimize these risks. Knowing the true value of a manure application can help you justify the extra management around making it work for you.

Manure adds nutrients and micronutrients: Nitrogen values vary greatly with the type of manure, the bedding used if any, how it has been stored and handled and when it is applied. The following chart adapted from the Agronomy Guide, OMAFRA Publication 811, gives some sample values for solid manure. Keep in mind that manure will continue to release some nitrogen for several years.

* approximate value based upon spring applied, immediately incorporated and on a N- P2O5- K2O value/lb of $0.40-0.35-0.17.
Source: OMAFRA NMAN 2001 software

In addition to N, P and K, manure can be a source of sulphur and micronutrients. Research indicates that micronutrient levels of 0.02 (Mn, Zn) to 0.005 (B) per cent of dry weight occur in some manures. This isn't a lot. For example, a 10 ton per acre application of solid beef manure has 28 % dry matter. This translates to about 1 lb. each of manganese and zinc and less than half a pound of boron. Plant availability of these micronutrients may vary.

Manure applications can have a liming effect. The manure can help to maintain or increase pH levels even when acid forming nitrogen fertilizers were used. An eleven-year project in Vermont involving manure application on continuous silage corn saw pH levels rise 0.2 and 0.3 pH units after annual applications of 10 ton/acre and 20 ton/acre dairy manure.

Manure adds organic matter. Manure applications as part of a berry crop rotation add organic matter to the soil. After years of intensive production many sandy loams have organic matter levels of less than 2 per cent. This increases the risk of herbicide injury and has other negative impacts. For example on a loamy sand a 0.5 per cent reduction in organic matter will result in a 15% reduction in nutrient holding ability and a 12 % reduction in water holding capacity (or 1 to 2 fewer days between irrigations). You can reasonably expect the reverse to happen if you can raise the organic matter level by 0.5%, although this will take time and a continued effort at soil building.

Manure improves yield: Research in the UK suggests that manure applications improved the water holding capacity of a sandy soil for potato production to an estimated yield improvement of 2.5 t/ha. Long term rotation work in Maine indicates that rotation with manure can improve yields by 20% under dry weather conditions. Yield gains were not due to additional nitrogen from the manure because the fertility program was adjusted for the manure application. The explanation for the yield increases is the soil structural changes, improvements in water intake and release and changes in the soil life that may have reduced the influence of disease organisms.

Best Management Practices for berry growers using manure:

• Maximize the period between when manure is applied and when the crop is harvested. Incorporate manure into the soil before planting, and do not harvest berries in the same year that manure is applied.
• Do not use manure for side-dressing.
• If animal manure is stored on the farm, ensure that contamination from wind drift to adjacent crops or harvested produce cannot occur. Ensure there is no potential runoff into irrigation water sources.
• Other best management practices for manure can be found in "Keeping Berries Safe, a Grower's Guide to Preventing food Borne Illness from Berries Crops" (call 1-877-424-1300 for a copy), and in the Best Management Practices Publications.

Using manure can be a valuable production practice for growers who have an available supply and follow best management practices for storage and application.

Related Links

• Best Management Practices Publications
• OMAFRA Environmental Management Website