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Dan Wofford, Jr.
Western Polyacrylamide, Inc.
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November 27, 1995

SUMMARY: A newly developed type of ten-year “NO-IRRIGATE/ NO-WEED/NO-CULTIVATE” dryland vegetable gardening appears readily adaptable to small fruit production. The basic Hydrosource/DeWitt Sunbelt Dryland Gardening System consists of a long-lasting, synthetic, water absorbing cross-linked polyacrylamide (CLP) incorporated into the soil and covered with a woven, polypropylene weed/evaporation/erosion barrier with a highly effective UV blocker. First developed in Colorado in 1992, more than 200 of the Hydrosource/Sunbelt beds have been constructed in the U.S., Russia, Lithuania, and Germany. Serious scientific study of the system with small fruits is just beginning. The Hydrosource/Sunbelt System consists of the following three types of materials:

1) DEWITT SUNBELT: This woven polypropylene barrier has a proven 10-year record on Colorado Living Snow Fences and other windbreaks dating back to the first installations in 1985 (#1). Since UV damage increases at the rate of 4% per 1000′ of elevation per year, the longevity achieved to date by Sunbelt in Colorado at 5,000-9,000′ elevation sites bodes well for growers at Missouri’s lower elevations. An added advantage is that Sunbelt will allow passage of water at the rate of 8 gallons per minute per sq. ft. Sunbelt will also take heavy foot traffic with little damage, and appears to tolerate some occasional, light vehicular traffic when the ground is relatively dry and free of surface rocks. Perhaps the best advantage of Sunbelt is the fact that it offers nearly 100% weed control. This year we achieved nearly 100% elimination of established weeds, Johnson grass (Sorghum halepense) and Bermuda grass (Cynodon dactylon) with Sunbelt on our farm in NE Oklahoma. However, it is our understanding that some pernicious grasses such as nutsedge (Cypernus rotundus) may penetrate the Sunbelt. Since the Sunbelt is a woven permeable material which allows “breathing”, its performance characteristics are much different from impermeable polyethylene in several aspects.

Research in 1990 and 1991 at the USDA Agriculture Research Service’s High Plains Research Station near Cheyenne, WY, found that available soil moisture under Sunbelt – without polymers – did not fall below 85% during the hottest and driest part of Wyoming’s summer (#2). However, without the polypropylene cover, nearby fallow ground dropped below 3% available soil moisture. The Sunbelt is widely used on Living Snow Fence and other windbreak plantings in the Western United States (#3), and in 1995 more that 1800 miles of such plantings using 6′ wide Sunbelt were installed (#4).

2) HYDROSOURCE CROSS-LINKED POLYACRYLAMIDE (CLP): Hydrosource CLP is a synthetic, water-absorbing polymer capable of absorbing more that 400 X’s its weight in rainwater, or 150-300 X’s under normal soil conditions depending on the amount of water-soluble salt (NaCl) present in the soil water. High quality, sodium-based CLPs of this type are capable of undergoing hundreds of freeze/thaw and hydration/dehydration cycles with little apparent damage. Estimated useful lifespan of high-quality CLPs in normal, undisturbed soil conditions is ten years.

3) FABRIC STAPLES: Initially 9-gauge, plain steel 6″ X 2″ and 4″ X 10″ wire staples driven into the ground at 45-degree angles were favored for the Hydrosource/Sunbelt System as it was being developed in Colorado. This type of wire staple has an estimated life span of 12 years in semi-arid Rocky Mountain areas, but shows signs of rusting much faster in the Ozark Mountains. Thus, we are considering the use of galvanized wire staples of similar sizes. The 9-gauge wire staples bend badly in extremely rock ground; but 8″ galvanized steel or aluminum gutter nails with plastic or metal washers appear to work much better under rocky conditions.

65,000 SQ. FT. PENNSYLVANIA APPLE ORCHARD TEST: Between April and early July 1995, Boyertown, Pennsylvania fruit grower Calvin Beekans constructed a dryland 65,000 sq. ft. Red Delicious apple orchard plot using the Hydrosource/DeWitt Sunbelt System (#5). He transplanted two rows, 8′ apart, of Red Delicious seedlings down the middle of two 12′ wide sections of Sunbelt and a “Brand X” fabric. A low-growing fescue is being seeded down the 20′ wide middles used for spraying harvesting and mowing equipment. Hydrosource Standard (2-4 mm) was disked into the portions of the plot under the fabric at rates of 12.5, 25, 50 and 100 lbs. per 1000 sq. ft. to 3″-4″ depths prior to fabric installation.

From the time of the last planting in late July 1995, this dryland site received only 0.7″ rainfall until the first freeze in September. Some lateral shoot growth at 25, 50 and 100 lbs. per 1000 sq. ft. Hydrosource CLP rates under Sunbelt was in the 12″-14″ range as opposed to less than 3″ for the control areas. Growth under the Sunbelt at the 12.5 lb. polymer rate was approximately 15″. Calvin Beekans judged the Sunbelt’s weed control as “excellent”, and also believes that virtually all erosion from the 4-5% sloped site will be eliminated due to the combination of Sunbelt and the fescue-sown middles. He estimates an annual drop in per acre herbicide costs from a current $85 down to $6-10. In addition to anchoring the fabric with 2″ X 6″ wire staples placed at 2′-3′ intervals along the outer edges of the Sunbelt, Mr. Beekans also covered the outer 6″ edge of the fabric with soil to avoid the accidental displacement of the fabric when high velocity orchard air blast sprayers are used. For the 1996 growing year he plans to develop an additional 2-4 acres of apples under the Hydrosource/Sunbelt System, plus 3 acres of nectarines and peaches. This test is being monitored by Drs. Robert M. Crassweller and Michael D. Orzolek, Department of Horticulture, Pennsylvania State University. (Note: Dr. Crassweller received an October 1995 $US8,000 Penn State internal grant which focuses on weed control and growth enhancement with the Hydrosource/Sunbelt System.) (#6)

HOPKINS RASPBERRY/BLACKBERRY/BLUEBERRY TRIAL (PEYTON, CO): In April 1992 Kirk and Bianca Hopkins constructed 500′ of contoured raspberry beds (200 Heritage, 25 Brandywine, 25 Royalty); also with blueberries (25 Bluecrop and 25 Northland) and blackberries (I 0 Illini Hardy) at a 7500′ elevation, 4-6% slope, 14″ annual rainfall site with frequent strong winds and bitterly cold winters (#7, 8 and 9). Hydrosource CLP rates were 0.5 to 4.0 lbs. per plant, thus giving each plant at the highest rate a water storage capacity in excess of 120 gallons.

The CLP was incorporated evenly within the 5′ wide contours to a depth of 12″, and then covered with 6′ wide DeWitt Sunbelt. During the 4 and 1/2 months from initial planting to the first frost, the control raspberries outside the system barely survived, growing only 2″-3″ to a total plant height of 4″-5″. However. the higher rates of CLP (i.e.. 2.0 to 4.0 lbs. per plant) produced 24″-30″ tall raspberry plants without Sunbelt. 36″-40″ with straw mulch. and 48″-50″ with Sunbelt. An on-site rain gauge recorded 11.35″ of rain during the 5-month growing season. This included three rains of more than one inch (only one of which generated any runoff) and 29 showers of .3″ or less (totaling 4.85″ of rainfall).

Many of the new Heritage canes were carrying more than 100 berries and blooms at the time of the 8 October 1992 killing freeze. The bitter Colorado winters at the 7500′ altitude, with temperatures sometimes dropping to lows of 25 degrees F for a week, killed the Heritage plants outright the first winter, and annually destroy all above-ground Brandywine and Royalty cane growth – thus preventing any second year and beyond fruit production.

Examination of the raspberry root systems showed growth well beyond the 6′ wide Sunbelt into the 14′ grass-covered middles. Strong grass/weed competition in the middles, plus increased evaporation, probably eliminated some growth potential. Had the Hopkins not lost the plants to winterkill, subsequent “U-Pick” raspberries and blackberries would have been planted 100% under connecting strips of 15′ wide Sunbelt for maximum evaporation, weed and erosion control.

RUSSIAN RASPBERRY/BLACK CURRANT/SEA BUCKTHORN/ CHERRY TEST: The first large scientific study of the dryland Hydrosource/ DeWitt Sunbelt System was a 1994 replicated small fruit trial with 216 raspberry, 96 black currant, 72 cherry and 72 common sea buckthorn plants by the Russian Research Institute of Agroforestry (VNIALMI) at Volgograd, Russia (#10). Latitude of the Volgograd site approximates the North Dakota/Canadian border, with an annual rainfall of 350mm (14″). Volgograd only received 85mm (3.5″) of rainfall during the 1994 growing season, thus making it one of the driest summers in the area’s history. A portion of this test involves a simple water-catchment system off an equipment storage building to double the area’s 14″ annual rainfall (# 11).

The Hydrosource/Sunbelt System resulted in a 12% improvement over the control in initial plant survival tests. Two variants of the Hydrosource/Sunbelt System resulted in 50-85% enhanced plant growth in contrast to 12-19% growth increase for the control plants. VNIALMI also estimates that weed suppression by the Sunbelt will save 250-500 labor hours per hectare (114-227 hours per acre).

NO-TILL VEGETABLE SYSTEM ADAPTABLE FOR NO-TILL SMALL FRUITS: In 1995 we successfully grew more than 12,000 sq. ft. of no-till cantaloupes, watermelons, okra, corn, marigolds, strawberries, blueberries, etc., on our farm in Northeast Oklahoma. The majority of these demonstration beds at various CLP rates were constructed simply by spreading the Hydrosource crosslinked polyacrylamide over the unplowed ground, and covering. the plots with tightly-stretched DeWitt Sunbelt. A similar Hydrosource/Sunbelt no-till, irrigated bed at a 9″ annual rainfall site at Merced Junior College (Merced, CA) showed little yield difference with controls using the conventional version in which the CLP is incorporated into the soil under the Sunbelt (#12). Another 1995 test using the no-till method has been completed by the VNIALMI/Astrakhan Substation, located at an 8″ annual rainfall site at the confluence of the Volga River and the Caspian Sea (#13). While the primary goal of tests at these three Oklahoma, California and Russian sites is to develop the technology for use in East African refugee camps, the same technique should be easily adapted for use with small fruit operations.

SUITABILITY FOR EXTREMELY ROUGH SITES: Based on ongoing tests at the three no-till Hydrosource/Sunbelt sites above, it now appears that we can grow NO-TILL vegetables and small fruits at virtually any site that will grow weeds and grasses. This will likely include sloped and rocky sites where conventional cultivation is difficult or even impossible.

A successful 4500 sq. ft. no-till cantaloupe bed of this type was constructed in spring 1995 on our farm in Northeast Oklahoma in a rocky hay field which had not been plowed since 1953.

In addition, we constructed a productive 15′ X 25′ cantaloupe bed simply by stomping down 6′-7′ tall Johnson grass and covering it with Sunbelt, plus three 15′ X 160′ cantaloupe/watermelon/Indian corn/okra/strawberry beds directly over unplowed Bermuda grass/vetch beds. Planted into moist ground on 6 July 1995, the cantaloupe bed over the Johnson grass received only 1.65″ of rainfall for the first 72 days after transplanting.

STRAWBERRIES: In addition to elimination of irrigation for strawberryproduction for Missouri, the Hydrosource/Sunbelt system offers nearly 100% weed control. We started experimenting with strawberries in Colorado at a 16″ annual rainfall site with three Tri-Star plants which have been producing well without any irrigation for the past three years. Currently some limited growing experiments are being conducted on two farms in NE Oklahoma with both day-neutral (primarily Tri-Star), and June-bearing strawberries (Chandler and Cardinal). Our goal is to develop the best planting methods through the Sunbelt. Strawberry tips were grown for 10-days in 4″ X 1″ split P.E.T.G. tubes (#14) for transplanting into 1 and 1/2″ to 2″ slits in the Sunbelt. Six month growth of those plants which survived the hot transplanting days in June and July appears to be normal through the 2″ slits. The most promising method being explored is to plant with the same 4″ X 1″ tubes through 1 and 1/2″ holes burned in the Sunbelt, although it appears to work well simply by planting strawberry transplants (sans the tubes) into the ground through the same size holes burned through the fabric. We have not seen any heat-related problems with established plants or berries. A major unanswered question is how June-bearing strawberries (e.g., Chandler/Cardinal) will handle the runner problem with this system.

SUMMARY: It is becoming increasingly obvious that the Hydrosource/DeWitt Sunbelt System has a bright future in small fruit and other areas (#15). It appears ideally suited for “U-pick” operations. and appears to be economical given its many advantages. The major research areas on which we are focusing are three-fold: a.) designing and constructing Hydrosource/Sunbelt beds for maximum weed, evaporation and erosion control. b.) determining the proper CLP rates for accelerated growth and maximum yields, and c.) experimenting to determine performance parameters with different types of small fruits grown with the system (#16). As expected. the highest-performing Hydrosource/Sunbelt beds are those which cover virtually all of the small fruit bed area. (#17). Development of the Hydrosource/Sunbelt System for vegetables will lead the way (#18) primarily because of one-year crop cycles, and this activity should be watched closely for ideas applicable for small fruit production.

1. Dr. Dale Shaw; Roy Shaw, DeWitt Tree Planter Notes; Vol. 5, Issue 1, October 1995.

2. “Weed Barrier Moisture Retention Study” (anonymous), October 1991, USDA/ARS High Plains Research Station, Cheyenne, WY.

3. Terry Wright, “New Tree-Planting Technology for the Prairie”, South Dakota Conservation Digest, Vol. 57, No. 4, 1990, pp. 2-4.

4. Dr. Dale Shaw; Roy Shaw, DeWitt Tree Planter Notes, Vol. 5, Issue 1, October 1995.

5. Personal communication with Calvin Beekans, 5 December 1995. 6. The title of the 1 Oct. 1995-30 Sept. 1996 Pennsylvania State University grant is: “The Use of Row Covers and Hydrophilic Polymers to Control Weeds and Improve Growth of Young Growth”.

7. Personal communication with Kirk and Bianca Hopkins, 6 December 1995.

8. Dan Wofford Jr.: “More on Water-Absorbing Polymers”, Hortideas Dec. 1992, Vol. 9, No. 12, pp. 133-134.

9. Dan Wofford Jr.: “Dryland Raspberries Grown with 14′ of Rain!”, Northland Berry News, Dec. 1992.

10. Dr. H. Mattis; Dr. S.H. Kruchkov; Dr. G. P. Arkhangelskaya; Dr. B. A. Mukhayev, “Polymers and Synthetic Mulching Barrier for Establishment of Windbreaks in the Arid Zones of Russia and the U.S.A.”, Russian Research Institute of Agroforestry;, Volgograd, Russia, Report on 1994 Research.

11. Robert Korick, “Even During Droughts Cisterns Deliver Rainwater”, Garbage, 1 July/August 1992, pp. 42-47.

12. Personal communication with Gary Clausen, Head of the Agriculture Department, Merced Junior College, Merced, California.

13. This documented VNIALMI/Astrakhan test is currently being translated for possible U.S. publication, as it may generate considerable interest because of its potential for vegetable production in African refugee camps.

14. The basic technology uses 3″ X 1/2″ P.E.T.G “Booth” tubes, and is being developed primarily for vegetable transplants. A total of 2268 plants per sq. yard (2806 per sq. meter) can be raised from seeds in #384 plug trays with this technique.

15. Karen Morley Smith, “Plastic Soil Covers Instead of Herbicides Spur Pear Growth”, Western Fruit Grower, March 1995.

16. Daniel J. Wofford Jr., “Worldwide Research Suggestions for Crosslinked Polyacrylamide in Agricultural Research”, 18 pp., The 1992 International Conference for Agricultural Research Administrators. Sept. 13-19,1992, McLean, Virginia.

17. Some installers are beginning to use hot-glue guns (on high settings) to patch Sunbelt to further minimize evaporation and maximize weed control around transplanted small berry plants.

18. Daniel J.Wofford Jr.; Michael D. Orzolek, “No Irrigating or Weeding for 10 Years”, American Vegetable Grower, Nove. 1993, pp. 30-32.

Copyright 1995 by Daniel J. Wofford, Jr, and Dale Greenwood.