UNITED STATES DEPARTMENT OF AGRICULTURE 

 BULLETIN No. 499 



Contribution from the Bureau of Plant Industry 

 WM. A. TAYLOR, Chief 



Washington, D. C. 



PROFESSIONAL PAPER 



February 12, 1917 



THE MULCHED-BASIN SYSTEM OF IRRIGATED 



CITRUS CULTURE AND ITS BEARING ON 



THE CONTROL OF MOTTLE-LEAF 



By 



LYMAN J. BRIGGS, Biophyslcist in Charge, C. A. JENSEN, Assistant 

 in Plant Malnutrition Investigations, and J. W. McLANE, Lab- 

 oratory Assistant, Office of Biophysical Investigations 



CONTENTS 



Introduction 1 



Cultural Practice in the Citrus Districts of 



California 3 



Flowsole 4 



Organic Mulching ......... 4 



The Mulched Basin 6 



Moisture Determinations in the Sunny 



Mountain Grove 7 



Soil-Moisture Measurements in Basins, 

 under Cover Crops and under a Soil 

 Mulch in the Vivienda Grove .... 8 

 Basin and Cover-Crop Experiments in the 



Victoria Grove 11 



Furrow Irrigation Often not Adequate . 13 

 Lateral Movement of Soil Moisture Very 



Slight 13 



Summer Cover Crops in Orange Groves 

 not Practicable without an Increased 

 Water Supply 14 



Organic Mulches More Effective than Soil 

 Mulches in Conserving Water .... 14 



Effect of Basining on Tree Growth . . . 15 



The Mulched Basin in Relation to Soil 

 Type 16 



Effect of the Mulched Basins on Soil Con- 

 ditions and Boot Growth 17 



Fruit Setting and Tree Growth as Influ- 

 enced by the Mulching Material ... IS 



Size of Basins . 23 



Cost of Preparing and Maintaining the 

 Basins and the Mulch 24 



Limitations of the Mulched -Basin System 25 



Humus Content of the Basins and the 

 Check Soils 26 



Summary 28 



WASHINGTON 



GOVERNMENT PRINTING OFFICE 

 1917 



