Double Cropping Effects on Forage Yields and The Water Balance in Southeastern Pennsylvania.

Double cropping is becoming increasingly common on Pennsylvania dairy farms as farmers struggle to produce enough feed and fiber for their cattle. This research studies the effect of using a winter small grain (rye: Secale cereale L. and barley: Hordeum vulgare L.) on main crop silage yields and soil water balance in no till. A continuous alfalfa treatment was added for comparative purposes. The components of the water balance measured were precipitation, runoff, drainage, and soil water content. Crop evapotranspiration was estimated using the Penman-Monteith method. Small grains harvested for silage were planted in the fall following the harvest of the main crops. Corn (Zea mays L.) and soybean (Glycine max L.) silage yields were not affected by double cropping. Total annual silage yields increased with double cropping compared to single cropping. Double cropping did not reduce runoff any more than single cropping rotations. Runoff was more affected by climatic conditions than by management practices such as crop intensification. Low antecedent soil moisture and low rainfall intensity were the influencing factors in this study. Drainage was no different in double cropping, single cropping and alfalfa (Medicago sativa L.) rotations except on a few dates when drainage in alfalfa was lower than in single cropping. Double cropping did not affect soil water content compared to single cropping. However, alfalfa lowered soil water content during a dry season compared to double and single cropping. Crop evapotranspiration was increased by double cropping during the fall and spring seasons. The water balance showed a likely over-estimation of drainage and possibly crop evapotranspiration during summer 2004 and 2005. Double cropping offers the potential to increase annual silage yields without affecting the water balance in Southeastern Pennsylvania.