Management Practices for Drip Irrigation in Baca County, Colorado

Management Practices for Drip Irrigation in Baca County, Colorado

Summary

The project coordinator has asked for, and received, a six-month no-cost extension to complete this project, which will allow the presentation of a workshop in Baca County on Subsurface Drip Irrigation (SDI) and to prepare a brochure of the project for distribution. It will also allow the producer to complete financial information on the project.

Introduction

The Ag Professional + Producer project was designed to help establish management practices for subsurface drip irrigation (SDI) on onions in Baca County, Colorado, that would improve germination, emergence and stands with resulting increase in yield, quality and returns. Due to a declining water table with diminishing pumping volumes, ag producers are looking for ways to improve irrigation efficiency, lower labor and production costs while maintaining and/or increasing yields and returns.

Three major problems with SDI confront ag producers, (1) tillage methods to maintain beds over subsurface driplines in the same location, (2) a means of protecting the small emerging onion plants from blowing sands in an area with high average winds, and (3) ways to improve movement of water from subsurface driplines to the shallow planted onion seed for adequate germination and emergence

Subsurface drip irrigation (SDI) applies water to crops in small amounts with little waste when managed properly. Water can be applied in amounts to match the crops’ water-use rates and can be as efficient as 98%. This is because the water is emitted below the ground surface and not subject to surface runoff and has limited evaporation. Most of the water lost by SDI is due to over-irrigation.

Producer Information

Brent Morris is a young farm operator in Baca County. He and his wife, Penni, own approximately 1600 acres of non-irrigated, dryland farm ground and rent 1780 acres of irrigated farmland. Dryland crops include wheat, grain sorghum and sunflowers. There are presently 1250 acres under center pivot irrigation and only 90 acres still being furrow irrigated because of the inefficiency of furrow irrigation and the high labor costs. Crops grown under irrigation are corn, grain sorghum, onions, sunflowers and wheat.

In 2003, a 170.1-acre drip irrigation system was installed with NRCS cost share and technical support, and the farm started growing cantaloupe, squash and onions. It was felt that these high-income crops were needed to justify this investment. The driplines were installed from 6 to 8 inches below the soil surface using 30-inch spacing of the driplines on 80-inch beds.

Brent provided two drip zones to be planted to onions in 2005 and one zone and part of another in 2006. One of the zones would be treated with AgriBlend, a blend of 40% HYDROGEL and 60% Zeolite. HYDROGEL is a water-absorbing cross-linked molecular structure polyacrylamide, and Zeolite is a water-transporting volcanic material. The Zeolite is used to help move the water toward the seed, and the HYDROGEL will absorb the water and hold it in the area of the seed.

DEMONSTRATION GOALS

MINIMIZING PRODUCTION PROBLEMS BY DEVELOPING MANAGEMENT PRACTICES THAT ARE ADAPTED TO THE AREA WAS THE GOAL OF THE PROJECT.

Because of this need to develop better management for SDI in this region, the following three practices were demonstrated at this site.

a. Tillage methods for preparing the beds are a problem. These beds need to remain in the same location because of the buried driplines, even though the lines were installed with the use of a GPS system. Disking was done with a specially designed disk to remake beds in the same location.

b. HYDROGEL, a water-absorbing cross-linked molecular structure polyacrylamide, and Zeolite, a water-transporting volcanic material, was used to help get water to the seeds and hold the moisture around the seed and seedling. The HYDROGEL used in this project is similar to that used with seedling trees.

c. Cover crops are needed to prevent wind damage to the emerging and young plants. The high winds in the area can severely affect crops in the seedling stage. Small grains, planted in late winter or early spring, were selected because of cost and availability of chemicals to kill the crop without injuring the seedling onion crop.

2005 Results

Yields calculated from the test plots taken from the AgriBlend treated zone averaged 986 bags per acre (50 pounds per bag), while the untreated zone averaged 944 bags per acre. There was no significant difference at the 10% level based on these results. These yields include only Jumbo, Medium and Pre-pack grades as culls and doubles were very minimal.

Percentage of onion grade also had little or no variation due to the addition of AgriBlend as both zones averaged approximately 62% Jumbos, 36% Mediums and 2% Pre-packs. Visually there appeared to be better stands in the AgriBlend treated zone than in the untreated zone.

2006 Cultural Practices

The beds were prepared by disking twice with the specially made Arizona Drip Wide Bed Disk from Coolidge, AZ. The beds were then worked four to five times with the culti-packer. AgriBlend was applied at the rate of 30 pounds per acre on beds with Gandy Boxes and incorportated with a culti-packer.

On March 8, Granero white onions were planted at the rate of 135,000 seeds per acre or about 3- to 4-inch spacing. Three rows, spaced 7 inches apart, were planted over the top of the driplines on each side of the 80-inch bed, about 12 to 14 inches from the center of the bed.

Then, on March 10, a combination of oats, triticale and wheat was planted in the middle of the bed. This combination of small grains was planted in an effort to reduce sand blowing and damage to the seedling onions.

The onions were fertilized with 150 pounds per acre of nitrogen as 32% liquid nitrogen and 50 pounds of P2O5 as 52% phosphoric acid through the SDI system. SELECT herbicide was sprayed at the rate of 10 ounces per acre to kill the small grains when the plant height was 6 to 8 inches and for weed control.

Cultural practices in 2006 were as follows:

1. 04-12-06 Sprayed 2.5 pts. Prowl H20 for pre-emergence weed control.
2. 05-08-06 Sprayed 8 oz. Goal and 10 oz. Buctril for weed control.
3. 05-16-06 Sprayed 10 oz. Select for control of unwanted grass and to kill the small grains planted to reduce sand blowing.
4. 05-17-06 Sprayed 12 oz. of Goal and 10 oz. of Buctril for weed control.
5. 05-29-06 Sprayed 2 gal. Warrior and 7.5 gal. Lannate for thrip control.
6. 06-01-06 Manual hoeing of weeds.
7. 06-10-06 Sprayed 2 gal. Warrior and 7.5 gal. Lannate for thrip control.
8. 06-24-06 Sprayed 2 gal. Warrior and 7.5 gal. Lannate for thrip control.
9. 06-28-06 Manual hoeing of weeds.
10. 06-29-06 Sprayed 10 oz. Select for weed control.
11. 07-18-06 Sprayed Pencozeb and Kocide for disease management.
12. 07-27-06 Applied 3 lb. Mankocide for disease management.
13. 07-28-06 Manual hoeing of weeds.
14. 08-03-06 Applied 3 lb. Mankocide for disease management.
15. 08-10-06 Applied 3 lb. Mankocide for disease management.
16. 08-17-06 Sprayed 24 gal. Dithane and 6.7 gal. Kocide for disease management.
17. 08-23-06 Applied 2 lb. Ridomil Bravo Gold and 3 lb. Mankocide for disease management.

The crop was irrigated to maintain good soil moisture throughout the season, and a total of 24 inches was applied.

Winds caused some blowing sand, but the stands of small grains and roughing up of the furrows prevented significant damage. Using both of these practices resulted in excellent stands of seeded onions.

Rains and cold weather was received starting September 1 before the onions could be harvested, causing a bacterial soft rot to infect many of the onion plants. As a result, the crop could not be harvested for commercial sale.

Six replications were taken throughout the field in both the AgriBlend-treated zone and the untreated zone on September 25. These yield samples were taken at the same locations in the field in the two zones.

NONE OF THE ONIONS WERE HARVESTED FOR PRODUCTION DUE TO DISEASE AND THE CROP WAS A TOTAL LOSS!

These results indicate that the addition of AgriBlend, HYDROGEL/Zeolite combination, significantly increased seeded onion yield and jumbo grade in 2006.

Jim Valliant, Colorado State University irrigation specialist in Rocky Ford, Colorado, as the Ag Professional, took plot yields and conducted the onion grading.

Brent and Penni Morris recorded the cultural practices throughout the year.

CONCLUSION

Tilling of the beds with the specially designed wide bed disk appears to be the best way to maintain the beds in the same location above the driplines and to prevent damage to the subsurface driplines.

Planting of oats in the middle of the beds between the onions and in the furrows as in 2005 or planting of oats, triticale and wheat in the middle of the beds between the onions and roughing of the furrows in 2006 did reduce wind damage on the young emerging and seedling onion plants. Planting the small grains in February or March allowed for sufficient growth to provide a wind barrier, but did not get too growthy to prevent killing of the small grains with chemicals.

The results of the addition of AgriBlend, a HYDROGEL/Zeolite combination, to the soil were not conclusive over the 2-year study period as significant increases in yield and quality were produced only in 2006. Additional demonstration work, under these conditions, is needed to confirm the results of applying AgriBlend on seeded onions using subsurface drip irrigation (SDI).

Many of the groundwater aquifers in Colorado, Kansas, Texas and throughout the Southwest are being rapidly dewatered. With fuel costs increasing, water tables dropping and pumping rates diminishing, pumping less water and being able to produce a comparable or better crop with SDI is an economically sound method of irrigation, especially in these windy, arid regions.

Many of these areas are faced with similar situations as in Baca County, Colorado. Use of this project information could help to prolong the life of their groundwater aquifers and sustain their economies.

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