Whole crop silage rice-barley double-cropping system using a direct harvesting method centered on the rice variety “Tachisuzuka”

In order to establish a whole crop silage (WCS) rice-barley double-cropping system in Fukuoka Prefecture using a direct harvesting method centered on the high-feeding-value rice variety “Tachisuzuka,” we examined yield and feed composition, and the relationship between transplanting or sowing period and ear emergence period in “Tachisuzuka” and WCS barley. In addition, we estimated the number of workable days while considering the harvest period and rainfall risk. Stem and leaf dry matter yield, high nutritional composition, and neutral detergent fiber digestibility were high in the “Tachisuzuka” variety, and little variability was observed in these characteristics between 20 and 60 days after the ear emergence period. Under standard cultivation conditions in Fukuoka Prefecture, the ear emergence period in “Tachisuzuka” was September 8 or 9, with very little variability due to transplanting period. In the case of WCS barley, rapid accumulation of dry matter yield and high nutritional composition occurred between 20 and 30 days after the ear emergence period. The ear emergence period in WCS barely cultivated under standard cultivation conditions was between March 27 and April 13, with considerable variability depending on sowing period. The findings of the study were as follows: (1) the harvest period for “Tachisuzuka” extends from September 23 to November 28, which includes 37.1 workable days, while the harvest period for WCS barley extends from April 16 to May 13, which includes the equivalent of 12.5 workable days for WCS rice; (2) the number of workable days for the entire double-cropping system is 49.7 days, which exceeds the 45 days required to keep harvesting and ensiling costs for WCS rice under 2,500 JPY per round bale.