His almond orchard was planted in the 1920's. So, there is a lot of history in his land. The orchard was planted on rolling hills in such a manner as to be able to grow and thrive without extra irrigation.
Rainwater is all the almond trees get.
This dry-farming method tends to produce almonds of much more intense flavor. Although the size of the fruit is smaller and the yield per acre is lower, the orchard is more sustainable. Dry farming conserves the critical resource of water. Water conservation is an issue that's going to become even more critical in the 21st century. Nuts are a wonderful source of protein.