MULCHED-BASIN SYSTEM OF IRRIGATED CITRUS CULTURE. 7 
common division bank of two basins.1 These square basins were 
mulched with manure in 1913, and in 1914 they received another 
mulching of manure (25 to 30 cubic feet per tree) and about 75 
pounds of barley straw on top of the manure. In the summer of 
1915, each basin received 14 bales of damaged alfalfa hay. 
The experiment included three rows of 16 trees each, making 48 
trees in all, or approximately one-half acre. The irrigation water 
was applied by turning the water into the upper basin of each row 
separately and allowing it to overflow into the next basin below, and 
so down the entire row. This method of irrigation was found, 
however, to be unsuitable to the deep sandy loam soil of this tract. 
The upper basins were under water too long a time before the lower 
basins were irrigated, and the water at the upper end of the row 
penetrated the subsoil below the zone occupied by the principal feed- 
ing roots of the trees, resulting in waste. In order to exercise both 
control and economy of irrigation water, it is necessary to run a 
furrow down the entire length of the row just outside the basins, so 
that each basin can be irrigated separately. This procedure was 
subsequently adopted and is the one usually followed by growers who 
are installing mulched basins on a commercial scale. 
MOISTURE DETERMINATIONS IN THE SUNNY MOUNTAIN GROVE. 
At intervals during 1914 duplicate soil samples were taken to a 
depth of 7 feet in two basins near the upper end of the middle row 
of basins, and similar samples were taken in two basins near the 
lower end of the same row, the two outside basined rows being consid- 
ered as guard rows. Similarly, duplicate samples were taken in the 
furrow-irrigated part of the grove two tree rows distant from the 
basined tract, the trees selected for sampling being opposite the 
basined trees sampled. 
In Table I are given the results of moisture determinations made 
in this experimental tract during the seasons of 1914 and 1915. In 
1914 the total moisture averaged about 3.7 per cent higher in the 
basins than in the check. The moisture available for growth in the 
first 3 feet of soil in the basins also averaged 3.8 per cent higher than 
in the check, being an equivalent of approximately 4 miner’s inches 
per acre flowing 24 hours. It will also be noticed (sec. C) that while 
the first 8 feet of soil under the basins never dried down to the 
wilting coefficient, the first 3 feet of soil in the check dried out below 
that percentage three times during the two years, and at four other 
1 While the mulched basin was developed independently by the writers, we have 
Since learned that Mr. J. R. Hodges installed several mulched basins in a grove at 
‘Covina, Cal., at an earlier date (1911). So far as the writers know, this was the 
first use of the system. 
