Range production as related to soil moisture and precipitation on the Northern Great Plains

This study was made to determine the relationship of the amount of soil moisture the preceding fall and current season April-July precipitation to native forage yields and gains per acre. The data showed highly significant correlation coefficients of .72 and .74 for the amount of fall soil moisture in the surface 3 feet and surface 6 feet, respectively, and native forage production the following season. When soil moisture was above or below average, forage yields also showed a positive relationship of being above or below average. On the area where forage yields were taken the soil was dry to a depth of 6 feet 44% of the time. When dry, 88% of the yields were below average. Increasing depths of moist soil produced, in general, increasingly higher yields of hay the following season. A highly significant correlation coefficient of .76 was obtained for April-July precipitation and yield the same season. Above average April-July precipitation was accompanied with above average yields 70% of the time. When the precipitation was below average, yields were below average 100% of the time. By adding the amount of soil moisture to the April-July precipitation a higher positive relationship was obtained for this value and yields than when either soil moisture or precipitation were used separately. There was a positive relationship between soil moisture and gains, but it was not as high as that for forage yields because of the additional variation brought in by the animal unit. On the area where gains were measured the soil was dry to a depth of 6 feet 42% of the time. When dry, 88% of the gains were below average. As in the case of forage yields, increasing depths of soil moisture produced, in general, increasingly higher gains. A highly significant correlation coefficient of .65 was obtained for April-July precipitation and gain. Above average April-July precipitation was accompanied by above average gains during 67% of the time. When the precipitation was below average, 80% of the gains were below average. When the amount of soil moisture in the fall was added to the April-July precipitation, a higher positive relationship was obtained for this value and gains than when either soil moisture or precipitation was considered alone in relation to gains.