"My analysis of this, coupled with experiments in composting, leads to the following conclusion: During the period of decomposition of the sawdust (hastened, no doubt, by the lime), the bacteria of decomposition fed so heavily on the nitrates in the soil that the plants were starved. When the material had reached the condition of humus, the bacterial activity decreased to the point where fertility was restored. "The above analysis accounts for the fact that coarse vegetable material, injures crops, when plowed under, for the current season. Fresh succulent material decays so quickly that it becomes almost immediately available, releasing its constituent plant food. "With proper conditions of moisture and aeration, sawdust, when mixed with quickly decaying material like kitchen garbage, can be reduced to an excellent, usable humus in three summer months. In fact, it is then better material than if permitted to lie out in the weather for fifteen years. "There is another factor I think important in tree growth, especially where summers are hot, and that is soil temperature. "For any of our nut trees I should say that an acidity test of pH 6 to 7 would be entirely satisfactory. If the soil is infertile, some form of humus should be worked in at the time of planting. If much such material is used, some lime may be added. Better yet, wood ashes and bone meal will furnish potash, phosphorus, and the lime necessary to correct acidity and maintain the phosphorus in an available condition. Add to this, proper drainage and cool soil achieved by, first, cultivation, and later by heavy mulching, artificial shading, or shrubby undergrowth extended outside the root area, and your tree should 'go to town.' When the tree is large enough to shade its own root area it will take care of its own soil refrigeration. Nature knew what she was about when she planted trees in forests. Trees require warm heads (sunshine) and cool feet (shade), just the opposite from us humans." Mr. Stoke's letter recalls a very ancient Arabian proverb connected with the date palm. "The date palm tree must have his head in hell and his feet in water." We are indebted both to Mr. Stoke and to the Arab scientists for many things.