HAY HARVESTING EQUIPMENT AND HARVEST STRATEGIES FOR QUALITY Dan Undersander 1 ABSTRACT If we understand and use the biology and physics of forage drying, not only does the hay or haylage dry faster and have less chance of being rained on, but the total digestible nutrients (TDN) of the harvested forages are higher. As mowing and conditioning equipment has evolved, some of the basic drying principles of forage have slipped by the wayside and we need to review them. The general principles are to mow alfalfa with either disc or sickle mower, condition with properly adjusted roller conditioner (flail is for grass hay), put into a wide swath, rake/merge into windrow while plant moisture is above 40%, and bale when adequately dry for storage, with or without preservative as necessary. Key Words: hay, conditioner, windrow, swath, alfalfa, merger INTRODUCTION Drying forage for hay has always been a challenge. While we cannot control the weather we can manage cut forage to maximize drying. The purpose of this paper is to give a few principles of hay and silage making and discuss machinery available relative to these principles. Then we will also talk about minimizing ash in hay to optimize the total digestible nutrients of the forage. Understanding Forage Drying Our understanding of conditioning and the need for conditioning has changed as we have revisited the factors affecting forage drying. In drying hay we need to maximize use of sunlight to enhance drying to minimize fuel use and cost of drying. Remember that, if we cut a 2 t/a dry matter yield, we must evaporate about 5.7 tons (1,370 gallons) of water per acre from the crop before it can be baled or 3 t/a (720 gallons) of water per acre before it can be chopped for silage. If we understand and use the biology and physics of forage drying properly, not only does the hay dry faster and have less chance of being rained on, but the total digestible nutrients (TDN) of the harvested forage may be higher. The general pattern of drying forages is shown in figure 1. When forage is cut, it has 75 to 80% water and must be dried down to 60 to 65% moisture content for haylage and down to 12 to 16% moisture content for hay (lower figures for larger bales). Initial drying occurs primarily through stomata in the leaves (Figure 1) (Jones and Palmer, 1932). Leaf tissue is high in water content (about 85% water) and contains about half of the whole plant                                                              1 Dr. Dan Undersander, (djunders@wisc.edu), Forage Agronomist, University of Wisconsin, 1575 Linden Drive, Madison, WI 53706; In: Proceedings, 2013 Western Alfalfa & Forage Symposium, Reno, NV, 11-13, December, 2013. UC Cooperative Extension, Plant Sciences Department, University of California, Davis, CA 95616. (See http://alfalfa.ucdavis.edu for this and other alfalfa conference Proceedings.)