16 BULLETIN 400, U. S. DEPARTMENT OF AGRICULTURE. 



mottle-leaf was not so conspicuous as it had been previous to pruning, 

 but the trees had made no visible response to the change in treatment. 

 A row of trees was basined in the latter part of April, and by the 

 latter part of July, a little over three months, there was a remarkable 

 improvement in the appearance of the basined row compared with 

 the check trees. There Avas a vigorous new growth of leaves, which 

 were large and velvety in texture, dark green in color, and almost free 

 from mottling, while the new leaves on the trees in the check row 

 were small and yellowish, more or less mottled, and never developed 

 normally. The accompanying photograph (PI. I) was taken about 

 the middle of July and shows clearly the improvement in growth and 

 color of the basined trees. 



THE VIVIENDA GROVE. 



The basined trees in this grove did not respond to the mulched- 

 basin treatment as rapidly as the basined trees in the Victoria grove, 

 but by the fall of 1915 there was a very distinct improvement in the 

 appearance of the basined trees when compared with the check trees. 



THE MULCHED BASIN IN RELATION TO SOIL TYPE. 



The early response of trees on heavy soils to the mulched-basiti 

 treatment appears to be due to the more uniform moisture condi- 

 tions under the mulch and also to the fact that more available mois- 

 ture is present in the basins than under the furrow method. The 

 heavjr soils of the Victoria groves in general do not take water well, 

 and there is very little lateral movement of water from the irrigation 

 furrows. Soil samples taken 18 inches from a furrow immediately 

 after irrigation frequently show-ed no increase in moisture due to 

 irrigation. It appears, therefore, that under such a furrow system 

 of irrigation, unless the number of furrows is greatly increased over 

 the usual number, the heavy soils are not thoroughly irrigated, so 

 that a considerable portion of the soil is devoid of available moisture 

 during part of the irrigation season. 



On the other hand, sandy loam soils, like those of the Vivienda 

 and Sunnj'- Mountain groves, take water more readily, so that after 

 an irrigation the moisture content of these soils is more nearly uni- 

 form and the available moisture is higher than in heavier soils under 

 furrow irrigation. The trees in the groves on the higher soils, 

 therefore, do not suffer so much from lack of water under the fur- 

 row method of irrigation as the trees on the heavier soils. 



Table VIII shows the available moisture after irrigation in the 

 Vivienda (sandy loam) and Victoria (clay loam) groves. The sandy 

 loam soils show more available moisture after irriiration than the 



