Alfalfa Responses to Irrigation Treatment and Environment¹

Abstract

Water management is critical for maximum production of alfalfa (Medicago sativa L.) with under irrigation resulting in loss of production and over irrigation resulting in a loss of stand. The purpose of this study was to determine the optimum irrigation rates under high evaporative demand. Growth of alfalfa was evaluated on replicated plots (6 × 6 m) established on a fine textured soil (Typic Torrifluvent, clayey over loamy, montmorillonitic, calcareous hyperthermic family) and differentially irrigated from July 1975 to January 1978. The irrigation treatments were applied at 56, 66, 75 (best estimate of Ep and 84% of pan evaporation (Ep) and described as dry, semidry, optimum and wet, respectively. Alfalfa yields increased with increase in water applied. Irrigation at 84% Ep for leaching did not enhance yield over the optimum water treatment possibly because of reduced stand from waterlogging. The protein concentration of alfalfa was higher in dry than in wet treatments in March and November. During the summer, plant temperatures in the dry treatment were up to 7 C higher than in the wet treatment.

Alfalfa Yield as Affected by Harvest Traffic and Soil Compaction in a Sandy Loam Soil

“…2A). This was a typical production pattern when compared to reports in similar climatic conditions (Donovan and Meek, 1983). Actual yields Year were low in the spring, improved as day length increased, and dropped in the fall.…”

Water-stress effects on forage quality of alfalfa

“…In trials on seven crop species, Jensen (1973) showed that alfal fa had the highest water consumption per year and the lowest water-use efficiency. Christian (1977) Alfalfa yields are a linear function of plant-water use (Bauder et al, 1978;Sammis, 1981;Donovan and Meek, 1983).…”

“…But the response of CP concentration in alfalfa to water stress seems to be in fluenced by additional environmental factors as well. For instance, Donovan and Meek (1983) found that CP concentration of forage was higher under low-moisture treatments in cool months but not in warm months. Nuttall (1975) Surveys of the literature (Wilson, 1982(Wilson, , 1983a, cover ing grasses and legumes in the tropical and temperate regions of the world, indicate that low soil moisture generally has a favorable effect on forage quality.…”

“…In some studies, plant response was related only to the amount of applied water during growth (Gindel, 1968;Janson, 1975), A refinement of this technique, which enables com parisons to be made among environments, is to express the amount of water applied as a proportion of potential évapo transpiration (Landsberg, 1967;Hanson, 1967;Snaydon, 1972a;Donovan and Meek, 1983). …”

“…For example, stomatal closure of alfalfa at midday has been reported to result in Tc of water-stressed alfalfa to exceed that of well-watered alfalfa by 8.50C in a study by Carter and Sheaffer (1983a) and by 7°C in a study by Donovan and Meek (1983). In the second method, the variability of re peated Tc measurements is used to indicate the level of in creasing water deficit.…”