Submitted to: Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 11/11/2008
Publication Date: 11/18/2008
Citation: Viramontes, U., Hernandez, G., Delgado, J.A., Wong, J., Avalos, J. 2008. Ecologically sustainable development in dairy farms II: Nutrient cycling. Paper presented in the FIL-IDF World Dairy Summit and Exhibition, Nov. 11-14-2008, Mexico City, MX. http://www/wds2008mexico.com/wds-conf/ Interpretive Summary: The region of Comarca Lagunera, or La Laguna, is located in north-central Mexico and covers ten municipalities in the state of Durango and five in the state of Coahuila. This region is representative of the intensive system of milk production, with the biggest dairy cow population, 415,000 animals that produce 20% of the milk in the country. According to the inventory of dairy cows in La Laguna, the estimated production of manure is 572,000 ton/year (dry weight); after considering losses, the manure in the region provides 14,000 ton of N, 8,000 ton of P2O5 and 12,000 ton of potassium (K2O). These amounts could be used to fertilize most of the agricultural area in this region dedicated to produce feed for dairy cattle, therefore recycling nutrients and reducing the risk of contamination by excesses of nutrients. However, the more common practice is to apply high rates of manure, above 80 ton/ha, in addition to conventional rates of fertilizers. With the high prices of fertilizers, it is important to search for alternatives to increase the use efficiency of nutrients, to lower fertilization costs for farmers. The cost of fertilizer and its application can represent from 30 to 50% of the cost of the forage crops production, so the use of manure as fertilizer can result in significant savings. In addition, the use of field sensors and computer models could facilitate the determination of how much manure and fertilizer is required to obtain adequate yields and to minimize risks of contamination to the environment. We are validating a Nitrogen Index to assess the effects of manure and fertilizer management practices on crop use efficiency and N losses. The computer program was developed by Delgado and collaborators at the USDA-Agriculture Research Service of the United States (USDA-ARS). The program inputs are: 1- crop information: 2- yield goal and root depth; 3- soil data: organic matter, inorganic N, pH; 4- manure analysis: N content, moisture content, rate of application; 5- fertilizers: products and quantities applied; 6-irrigation: amount and N content in the irrigation water. Initial results suggest that the Mexico forage N Index will be a useful tool for improving nitrogen management and nitrogen use efficiencies across the region.
Technical Abstract: In Mexico, there is not a specific regulation dealing with manure and wastewater in confined livestock farms. In the case of dairy farms that have agricultural areas for the production of forage crops, there are some "Good Management Practices", focused on the use of manure as a source of nitrogen and phosphorus for forage crops: • Estimate the production of manure, based on the size of the dairy herd. • Estimate the amounts of available nutrients in manure by means of lab tests. • Estimate the cropland required to dispose of manure properly, according to the nutrient requirement of crops. • Apply manure to meet the N and P requirements of forage crops, according to yield goals. • Estimate rates of manure as a function of N and P available to the crop, and according to the mineralization rate of each element. • Analyze the soil to know available nutrients to the crop, and to prevent excessive accumulations of P. • Analyze sodium and soluble salts in the soil to prevent excessive accumulation, as a result of continuous application of manure. There are some other options for handling manure, such as composting and biogas production. These options can be carried out within the dairy farm and they can follow the approach of recycling nutrients within the farm.