WATER REQUIREMENT OF ALFALFA. 5 



the moisture supply falls short of the amount necessary to produce 

 normal crops throughout the season, summer grazing appears to 

 afford a simple and practical means of obtaining a return from alfalfa 

 commensurate with the available moisture and at the same time 

 reduces the danger of drought injury. 



In the pot experiments already described, weekly cutting reduced 

 the total amount of dry matter produced to one-third the normal 

 crop. This would indicate that when the moisture supply is adequate 

 for continuous crop production throughout the season, close pasturage 

 or clipping would result in a marked reduction in the amount of 

 alfalfa produced. Consequently, where grazing is practiced greater 

 production can be secured by intermittent grazing; that is, by employ- 

 ing several fields which are pastured in rotation. 



SUMMER PASTURAGE OF ALFALFA EXTENSIVELY PRACTICED IN 



AUSTRALIA. 



Since the experimental work referred to above was completed, the 

 writers have learned that a practice similar to that suggested has 

 been gradually developed in Australia as giving the best return in 

 the management of Australian alfalfa land. The practice is to grow 

 a hay crop in the early spring and to pasture the alfalfa during the 

 remainder of the year. Aside from the hay obtained, alfalfa is very 

 valuable in Australia for grazing purposes, because it responds to 

 summer rainfall, while the native grasses, being annuals, afford no 

 late pasturage. On a large ranch or "station" near Wagga Wagga, 

 New South Wales, one of the writers recently saw 1,000 acres of 

 Peruvian alfalfa that is being handled under this combined system 

 of hay and pasturage. The alfalfa at this station carries three sheep 

 per acre during the summer, autumn, and winter months. About 

 the first of September (early spring) the sheep are taken off. The 

 alfalfa makes a luxuriant growth during the cool spring months, and 

 a crop of from 1,500 to 2,000 pounds per acre of cured hay is obtained. 

 The hay is produced when the weather is cool and the transpiration 

 rate low — in other words, when the crop is making the most efficient 

 use of the water supply. The normal rainfall in this region is about 

 21 inches and is quite uniformly distributed, each month having more 

 than 1 inch of rainfall and only two months (June and October, 

 corresponding in season to our December and April, respectively) 

 more than 2 inches. 



At another station an alfalfa field of 120 acres was seen, which is 

 being treated in the same way. The sheep are taken off the middle 

 of August, and the alfalfa is usually cut the last week in October. 

 The single cutting averages about 1 ton to the acre. The rainfall is 

 about 22 inches a year. 



This combined system of hay and pasturage has found much favor 

 in New South Wales and is carried out in a rolling-plains country on 

 loam or sandy-loam soils where there is no possibility of subirrigation. 



