XII Journal of Agricultural Research voi.xii 



Fig. 3. Diagrani showing the individual tree jdeld of the Valencia orange page 



grove 255 



4. Diagram showing the individual tree yield of the Eureka lemon grove . 255 



5. Diagram showing the individual tree yield of the seedling walnut 



orchard 256 



6. Diagram showing the individual tree yield of the Jonathan apple 



orchard 257 



7. Graphs of tlie reduction of the coefficient of variability by increasing 



the number of adjacent trees to the plot 261 



8. Graphs of the reduction of the coefficient of variability by increasing 



the number of trees to the plot 262 



9. Graphs of production, 32-tree plot, navel oranges (Arlington) 267 



10. Curve of yields of individual trees, navel orange (Arlington) 268 



11. Curve of yield of individual trees, navel orange (Antelope Heights). . 269 



Water Extractions of Soils as Criteria of Their Crop-Producing Power 



Fig. I. Graphs showing soils arranged with reference to yield and important 



characters 307 



Effect of Season and Crop Growth in Modifying the Soil Extract 



Fig. I. Design of soil containers 323 



2. Diagram of the arrangement of the soil containers 324 



3. Graphs of the nutrients extracted from soil 4 by varying the ratios of 



soil to water 336 



4. Graphs of the nutrients extracted from soil 5 by varying the ratios of 



soil to water 336 



5. Graphs of the nutrients extracted from soil 8 by varying the ratios of 



soil to water. Calculated to parts per million of dry soil 337 



6. Graphs of the nutrients extracted from soil 10 by var}-ing the ratios of 



soil to water 337 



7. Graphs of the yield of grain in 1915 and 1916, expressed as a percentage 



of tlie maximum yield 342 



8. Graphs of the seasonal studies of the water extract of soil 1, Yolo silty 



clay loam 343 



9. Graphs of the seasonal studies of the water extract of soil 2, Yolo silt 



clay loam 344 



10. Graphs of the seasonal studies of the water extract of soil 3 , Yolo silty 



clay loam 345 



11. Graphs of the seasonal studies of the water extract of soil 4, Yolo silty 



clay loam 346 



12. Graphs of the seasonal studies of the water extract of soil 5, Yolo silty 



clay loam 347 



13. Graphs of the seasonal studies of the water extract of soil 6, Yolo clay 



loam 348 



14. Graphs of the seasonal studies of the water extract of soil 7 , Hanford fine 



sandy loam 349 



15. Graphs of the seasonal studies of the water extract of soil 8, Fresno fine 



sandy loam 350 



16. Graphs of the seasonal studies of the water extract of soil 9, Kimball 



fine sandy loam 351 



17. Graphs of the seasonal studies of the water extract of soil 10, Tejunga 



fine sandy loam 352 



18. Graphs of the seasonal studies of the water extract of soil 11, jVIadera 



fine sandy loam 353 



