MULCHED-BASIN SYSTEM OF IRRIGATED CITRUS CULTURE. 5 
Prof. Fawcett had returned from a trip to Florida and Cuba and brought back 
reports of having seen very marked recovery of trees, apparently similarly 
affected, brought about by heavy mulch, we selected six rows 49 trees long 
through the very center of our worst affected area. We first plowed the ground 
and, after running three large furrows for irrigation, covered three of these 
rows, spaces and all, with manure and three of them with bean straw to a depth 
of 4 to 6 inches. From the road in the valley below looking up toward the hill 
slope where this orchard lies one can see these six rows standing out in contrast 
like a belt of green ribbon across a yellow background. It is remarkable, and 
all in nine months. Later observations from the near-by hills reveal the fact 
that the small tract mulched over two years ago is also darker green than the 
surrounding orchard, though the contrast is not so great, because it lay among 
healthy trees and was itself a group of normal trees.* 
While surface mulching of orchard trees in humid regions with 
organic material has long been practiced on a small scale, it has not, 
in the United States at least, been followed to any great extent. The 
results of recently reported investigations in Pennsylvania by Stew- 
art ? indicate, however, that surface mulches of strawy manure, alfalfa 
hay, or other organic material may be used with advantage and profit 
in the culture of apples on a commercial scale. Stewart summarizes 
his investigations in part as follows: 
In general the mulch treatment, reinforced by outside materials, has been 
most efficient in improving the yield, growth, and average size of fruit in 
orchards up to about 20 years of age. In older orchards it has been surpassed 
slightly by tillage and cover crops, unless accompanied by adequate fertilization. 
It has also been most efficient in conserving moisture in all cases that have been 
determined. 
The crop value of the present mulch has averaged 764 bushels per acre 
annually in the seven normal comparisons available. Its annual gain over 
tillage and cover crops has averaged 15.8 bushels per acre in the same experi- 
ments. The mulch is therefore a valuable treatment when properly managed 
and when mulching materials are available at not over $7 per ton, unless 
tillage is not practicable. All mulches should be kept at least a foot away from 
the tree trunks, and a greater distance is desirable as the trees enlarge. 
Faweett,? of the California Citrus Experiment Station, has re- 
cently made the following observations regarding the use of organic 
mulches in citrus groves in Cuba, where the distribution of the rain- 
fall is similar to that in Florida, the greater part occurring during 
the summer months: 
At Herradura, Prof. F. 8. Earle showed the writer a grapefruit grove on clay- 
loam soil underlain with stiff clay, where part of the grove had been mulched 
1As this bulletin is going to press Mr. Culbertson informs the writers that the six 
rows of mulched trees yielded 36 per cent more fruit in 1916 than the adjacent six rows 
of unmulched trees, although at the beginning of the experiment the rows selected for 
mulching were the lowest yielding rows in the block. At the present time (winter of 
1916-17), however, the mulched rows are again becoming yellow, so that the future 
success of the surface mulch is still uncertain. 
2Stewart, J. P. Cultural methods in bearing orchards. Penn. Agr. Exp. Sta. Bul. 141, 
28 p., 4 fig. 1916. 
’Fawcett, H. S.A comparison of some citrus conditions in Florida, Cuba, and 
California. Jn Mo. Bul. Cal. State Com. Hort., v. 5, No. 9, p. 321-337, fig. 108-117. 
1916. 
