A weekly report prepared by the staff of the Ministry of Agriculture, Food and Rural Affairs (OMAFRA). If you require further information, regarding this report, call the Elora Resource Centre at 519-846-0941. Office hours: 8:30am to 4:30pm. For technical information, call the Agricultural Information Contact Centre at 1-877-424-1300 or visit the OMAFRA website: www.ontario.ca/omafra.
WHAT IS THE IMPACT OF MANURE ON SOIL ORGANIC MATTER?
Regular manure applications combined with forage-based rotations are the envy of crop producers when soil organic matter (SOM) levels and soil resilience are considered. What is the actual organic matter benefit from manure to the soil, and how does that vary with different types of manure and organic amendments?
Livestock manure is an excellent source of nutrients and organic matter for the soil. However manure composition, soil characteristics and application management will impact the nutrient and organic matter value.
Factors Impacting Nutrient & Organic Matter Benefits
Manure composition varies with animal type, age, feed ration and the environment.
– Ruminants usually have forage based diets, while monogastrics (i.e. hogs) are fed grain-based rations. Beef and dairy manure contain undigested forages and often contains bedding materials. These materials are high in cellulose and lignin and take longer to decompose in soil when compared to the less complex sugars from undigested corn.
– Animal stage / age will influence the amount of feed consumed, but also dictate the protein and mineral content.
– Ration formulations vary. High production phases require more concentrated diets, including phosphorus, potassium and trace elements such as calcium. Regular and high application rates of manure will build up phosphorus and potassium levels, pH (in acidic soils). Micro-nutrients deficiencies, including zinc and sulphur, are rare with regular applications.
– The animal environment (housing) determines the amount and type of bedding. The storage method and additional materials or wastewater determine the manure dry matter content. The carbon-to-nitrogen (C:N) ratio of wood chips (200+) will be much higher than straw (50 – 80).
– The C:N ratio is the proportion of organic carbon to total nitrogen of manure or organic material. The nitrogen is a food source for the soil micro-organisms while they break down the carbon material. When that process is complete, the soil microbes die and decompose. The microbial nitrogen is then returned to the soil and becomes available to the plants. This is considered the “organic nitrogen” component. How long this process takes depends on the ratio of carbon to nitrogen in the material.
– Manure or organic material with C:N ratio under 20:1 is considered ideal for crop production. When there is not enough nitrogen in the organic material to break down the carbon, the micro-organisms utilize nitrogen from the soil. When C:N ratios are higher than 25 to 30:1, it could result in a nitrogen deficiency of a crop that relies on soil nitrogen, such as corn.
Manure will add organic matter but also adds nutrients. Over-application of nutrients could lead to crop damage or nutrient losses into the environment. In addition, any benefits from soil organic matter are easily negated if soil compaction results from application on unfit soils.
Coming Events:
Dec. 11 – BDO’s Ontario Agriculture Roadshow, Fergus Community Hall, Fergus. Space are limited, please visit http://bit.ly/1MRRNny to register
