Yuma Ag and You: Transitioning into Summer Crops

Bobbi Stevenson-McDermott   Feb. 15, 2015 publication

Spring has sprung it seems here in Yuma! Temperatures are certainly uncharacteristically warm for February. Along with the warmer weather, portions of our farmlands are also changing. The produce season which started in August 2014 is winding down and will be mostly over by April. Fields that sparkled with all shades of red and green produce in straight rows are giving way to flat fields with young wheat; rows of melon transplants or seed; Sudan grass in March and newly planted cotton fields which have yet to stick their leaves above the soil.

These are the primary ‘summer crops’ that are seen from now until August. In addition, broccoli, onion, artichoke and cauliflower seed fields are beginning to bloom making work for the bees.

The wheat market is stronger than the cotton market this year, so there will be more acres of Duram wheat planted. Wheat yields range from 3 to 4 tons per acre or 120 to 140 bushels per acre. The wheat we grow is normally used for pasta and much of the ‘Desert Duram’ goes to Italy for pasta production. Cotton can be planted in February as long as soil temperatures are 60 degrees or more. Farmers are always concerned about a late freeze but normally plant anyway! Melons used to be grown from seed, but more growers are going to the use of transplants. Since the popular varieties of melon seed have grown more expensive, it is practical to use transplants since the grower is assured of a healthy plant. Watermelons, seedless watermelons, cantaloupe, honeydew and specialty melons are all grown with harvest starting in late May, depending on the weather.

Wheat harvest, for the usual December 1 planting date, starts in late May. The wheat fields planted after December 1 usually require an additional 200 pounds of seed each week past the normal date. This is because wheat planted and allowed to go through cold weather produces multiple seed heads. To achieve the same yield, more seed must be planted since the weather is much warmer and the multiple seed heads do not develop.

Cotton harvest normally starts in July and depending on when the field is needed for produce, may be harvested into October. Sudan grass is a forage crop which is great for the soil. Most of the Sudan grass grown in Yuma is baled and then shipped to Japan as forage for their livestock, since there is not enough land to produce forage there.

It is important that farmers follow a crop rotation that alternates tap rooted crops (most vegetables) with a fibrous rooted crop such as corn, Sudan Grass, millet, barley or other grass type crops. Vegetables have a shallow root zone, 12 to 18 inches and much of the fertilizer used during their growing season moves below where the roots can pick it up. The fibrous rooted crops have a 30 to 36 inch root zone and often do not need to be fertilized during their growing season as their roots pick up the nutrients left behind by the vegetable crop. In addition, the soil in vegetable is mostly saturated below 18 inches. It is best if no deep tillage is done between the vegetables and the secondary crop, because it will cause compaction, destroy the soil structure and adversely affect water intake rates. After the fibrous rooted crop has sucked all the moisture out of the top 36 inches of soil, use of a ripper or tillage implement can be very effective in breaking up the compaction caused during produce season by having to harvest in wet fields. Good soil management means better crop health and yields.