WaterConservation Education with a Rainfall Simulator

Hans Kok* and Shelly Kessen

ABSTRACT A rotating boomrainfall simulator was developed for research purposes in the 1960s (Swanson,1965). Simulators Rainfall simulatorsare beingtaken beyondresearch bound- are still used for research (Meyer, 1988), but are also pro- aries as an educationaltool to reach producers.Simulators visually demonstratethe benefits of increasedcrop residue for viding visual demonstrations for producers who may be improvedwater conservation and decreased . reluctant to implementconservation tillage strategies for Educational rainfall-simulator demonstrationshave found water and soil conservation purposes on their farms. As part favor with CooperativeExtension Service (CES)agents and of a targeted educational effort in eastern Nebraska,a simu- NaturalResources Conservation Service (NRCS)personnel lator was used as a componentin a comprehensiveconser- they stress the value of low- andno-tillage farmingsystems. vation tillage program(Dickey et al., 1991). In V’trginia, Between1992 and1995 a rotating boomrainfall simulatorwas conservationists used a rainfall simulator in the Chesapeake used as part of a comprehensivewater conservation education Bay Programto educate farmers, public officials, and the programin Kansas, Colorado, Missouri, and Oklahoma.One general public about the projected benefits of best manage- or two demonstrationsper day were performedat different ment practices implementation for water quality, such as locations andas manyas eight demonstrationsper day were conservationtillage and no-till (Dillaha et al., 1988). doneat one location to showthe effects of cropresidue man- Producers, in general, are loyal to tradition and do not agement on water conservation. Morethan 8000 people, readily accept conservationtillage practices, especially no- includingproducers, agribusiness representatives, agency per- till farming. Manyare concerned about increased disease sonnel, urbancitizens, andstudents witnessedthe 167 demon- potential, possible yield reductions, increased strations at 77 different sites. Theprogram was appreciated by requirements, and soil limitations (Shelton et al., 1991). the public as indicatedby surveyresults. Widecoverage of the Levels of adoption of water conservation management demonstrationsby local andregional mediawas received, and practices increase whenfarmers becomeaware of a problem a video wasproduced. Rainfall simulatordemonstrations are a on their operation, recognize the cause, and obtain a work- powerfultool to promotewater conservation, and provide a ing knowledgeof available local assistance. It is important goodbackground for discussionof topics such as conservation tillage andcrop rotation. that they understand that implementationof available tech- nologies is economically feasible and supported by locally relevant demonstrations(such as the rainfall simulator pro- ATERCONSERVATION is a major concern for crop pro- gram) (Nowak, 1985). Wduction in Kansas. Throughoutthe state, crops suffer annually from periods of water shortage, while muchof the METHODS needed rainfall is lost in evaporation and runoff (Greb, Adoption of conservation practices has been lacking in 1983). In addition, an estimated 106 million Mg(117 tons) Kansas, so in 1992 a comprehensiveprogram was started to of topsoil per year is lost due to water and wind erosion promotewater conservation. A rainfall simulator was used pressures (USDA-SCS,1992). Erosion is detrimental in field-day programs to help demonstrate the superior agricultural productivity, but a more immediatethreat to choice of high residue comparedwith low or no residue for producers in western Kansas is inefficient water usage. moisture conservation. Water conservation is vital in the semiarid regions of the Lowrainfall and high winds characterize the western state. region of Kansas, making it a prime target for high water Conservation tillage is one of the most effective and loss and wind erosion. Bare soil conditions create increased least costly methods of improving soil water retention, soil sealing, poor , increased water runoff, and reducing soil erosion, and conserving labor and fuel (Dickey low capture rates for snow. Rainfall simulator demonstra- et al., 1991). Increased residue cover from conservation tions were used to showthat crop residue increases water tillage offers manybenefits to the producer. Crop residue conservation and reduces water erosion. will improve water infiltration, reduce evaporation, and The University of Nebraska’s (UN-L) rotating boom maintain organic matter content (Unger, 1994). In addition rainfall simulator was used in 1992 to perform 28 CES to improvingthe cropland, conservationtillage is also essen- demonstrations at 20 locations throughout Kansas. Basedon tial for farmers to remaineligible for FarmProgram benefits favorable audience responses, a similar rainfall simulator on highly erodible land under conservation provisions in the was built by Kansas State University (KSU)with a joint 1985, 1990, and 1996 farm bills. grant from the Kansas Agricultural Experiment Station (AES) and CES. Approximate cost of building the machine was $15 000. H. Kok,Dep. of Agronomy,2014 Throckmorton Hall, KansasState Univ., Manhattan,KS 66506; and S. Kessen(formerly Kansas State Univ.), Fleishrnan-Hillard,2405 Grand Blvd., Suite 700, Kansas City, MO64108. Abbreviations:CES, Cooperative Extension Service; NRCS,Natural Contribution94-388-E of the KansasState Univ.Agric. Exp. Stn. Received ResourcesConservation Service; UN-L, University of Nebraska-Lincoln; 1 Apr.1996. *Corresponding author ([email protected]). KSU,Kansas State University;AES, Agriculture Experiment Station; USEPA,U.S. EnvironmentalProtection Agency; SCS, Soil Conservation Publishedin J. Nat.Resour. Life Sci. Educ.26:20-23 (1997). Service;FSA, Farm Services Agency.

20 ¯ d. Nat. Resour.Life ScLEduc., VoL 26, no. 1, 1997 A wide variety of rainfall simulators is available for demonstrations.Cooperation at the local level wascrucial to demonstrations(Fermanich et al., 1995; Dillaha et al., 1988; the success of the demonstrations. Countyextension agents Beck, 1984; Brakensiek et al., 1979), ranging from small and NRCSpersonnel were in charge of organizing and table-top units to large systems that take manypeople and advertising the field day. They also madearrangements for muchtime to install. Weopted for the large, relatively water supplies, demonstrationlocation, and site preparation. portable, but fairly expensive rotating boomdesign for sev- Expenses were kept to a minimumbecause few supplies eral reasons. From the 1992 demonstrations, we knew to were required on the demonstration site. Local volunteers anticipate large audiences. Small simulators, and the use of assisted in preparing the site and setting-up the simulator. curtains would not be feasible trader the frequently windy Set-up and plot preparation required about 2 h. Demon- conditions. Also, a large simulator, placed on representative stration-site breakdownwas completedin less than 1 h. field conditions for the area, gives a muchmore convincing The runoff and erosion processes were shownon four demonstrationof water conservation, than does a small sim- plots of 1.5 by 9 m (5 by 30 feet) under the simulator. The ulator. plots were surrounded by metal borders with V-shapedcol- The machineis self contained on a double axle trailer lectors at the bottom (Fig. 1). Waterrunning off the plots (2700 kg, 6000 lb), which is pulled by a three-quarter ton was guided over white PVCgutters to visually display its pickup truck. A 3.7 kW(5 hp) gasoline engine powers quantity and color. No runoff measurementswere madedur- hydraulic pumpfor rotation of the booms,and cylinders for ing the demonstrations; only visual differences were shown. leveling the machine. A second, identical engine powers a Imhoff cones were used to showthe differences in runoff self-priming 8 L/s (130 gpm)water pump.A wide variety and sediment discharged by the plots. Water intake was couplings is available to hook up to different water sources. expressedas a function of total rainfall before runoff began. Construction details of the KSUmachine, or of the approx- Rain gauges were installed, and white PVCpipes were ver- imately 15 similar units that exist in the USA,have not been tically inserted into the soil to showthe difference in splash published. Each machineis an adaptation of an earlier ver- erosion betweenbare and residue-covered soil (Fig. 2). sion. For details on constructing a rotating boomrainfall The plots were tilled extensively before the demonstra- simulator, contact the author. tion, and crop residue was removed. Most plots were on Both rainfall simulators (KSUand UN-L)use 227 L conventionally tilled summer-fallowground, and little plot water/min (60 gpm) to apply a rainfall rate of 63.5 mm/h preparation was required. Residue was then placed on the (2.5 in/h) to a 15-m(50-foot) diameter circle. Weused plots to achieve specific ground cover rates. For most intensity (the sameas in the 1960s design) becausethe aver- demonstrations wheat (Triticum aestivum L.) straw was age 1-h storm intensity for Kansasis 6.6 cm(2.6 in) (per- used, and sometimes corn (Zea mays L.) or sorghum [Sor- sonal communication, M. Knapp, climatologist, Kansas ghumbicolor (L.) Moench]residue was used. Somedemon- State Univ.). The KSUmachine can also apply rainfall at an strations were done on no-till ground, and low residue lev- intensity of 127 mm/h(5 in/h). els were obtained by removing residue with a hand mower Distribution of rainfall over the plot area wasdetermined and rake. Becausethe underlying soil surface was similar on by operating the simulator over an 18 by 18 m grid (60 by all plots, the demonstratedeffects weredue solely to residue 60 feet) with 120 mL(4 oz) plastic cups placed every 1.5 cover. (5 feet) for 26 min. This test was repeated twice, and showed To showthe effect of residue on water infiltration, and that depth of water in the 15 m (50 feet) diameter circle runoff and erosion, two side-by-side plots had very differing the simulator had a coefficient of variation of 5%;29.2 mm residue levels. One plot had more than 80%coverage and + 1.5 mm(1.15 in + 0.06 in). the other had less than 10%. Dependingon local conserva- All plots at the demonstrationsites were wetted equally tion requirements, the remaining two plots showedcontour before the demonstration to ensure rapid occurrence of farming, partial terracing, or differing crop residue levels runoff during the actual demonstration. Between6 and 50 (usually 10, 20, or 30%ground cover). mm(0.25-2 in) of rainfall were usually needed to generate runoff from bare soil during this prewetting. The actual RESULTS AND DISCUSSION demonstrations lasted 15 to 20 min, equivalent to 15 to 20 mm(0.6-0.8 in) of additional rainfall applied. The total Between 1992 and 1995 the simulator was used in 167 water requirement per demonstration was up to 15 m3 (4000 demonstrations at 77 sites in Kansas, Colorado, Missouri, gallons). Waterfrom a variety of sources was used, such as and Oklahoma.More than 8000 people including producers, fire hydrants, irrigation wells, fertilizer trucks, fire trucks, agribusiness representatives, agencypersonal, urban citi- and farm ponds. The water supply was usually donated, and zens, and students witnessed the rainfall simulator demon- local producers volunteered their farms for the demonstra- strations. Financial support was obtained from U.S. tion site. Environmental Protection Agency (USEPA)Section 319 Generally, the rainfall simulator demonstrationswere not Water Quality funds and from the Soil Conservation Service featured as stand-alone programs, but were integrated into (SCS) in 1992-1993,respectively, to hire student labor experiment station field days and other extension programs assist with the demonstrations. One or two demonstrations such as demonstrations of terrace maintenanceand residue per day were performed at different locations and as many management.Field day involvement by several local enti- as eight demonstrationsper day were done at one location. ties including CES, NRCS,chemical and equipmentdealers, Presentations from NRCSand Farm Services Agency and farmer coops resulted in larger attendance and increased (FSA) officials often preceded the demonstration. Before audience interaction, comparedwith stand-alone rainfall the simulator was started, conservation complianceissues

J. Nat. Resour.Life Sci. Educ.,VoL 26, no. 1, 1997¯ 21 Fig. 1. Kansas State University rotating boom rainfall simulator in operation, showing plots with varying amounts of crop residue applied. Note the white PVC gutters to show the color of runoff water. Also note the white PVC pipes in front of the machine to demonstrate splash erosion. and methods of measuring crop residue cover were dis- ground cover. Up to 75 mm (3 in) of rainfall were applied to cussed. As the rainfall started, the relevance of those issues the soil, however, over the course of 1 d, during multiple to water infiltration and soil erosion was demonstrated. demonstrations. All low residue plots, which had less than Throughout and following the demonstration, water conser- 10% ground cover, produced runoff after 6 to 50 mm vation, crop rotation, productivity, and profitability were (0.25-2 in) of rainfall. Soil covered with residue amounts as discussed. low as 30% had substantially more water infiltration than Demonstration sites represented annual precipitation bare soil. amounts from 400 to 1000 mm (16-40 inches). Soil textures The difference in water infiltration among plots was ranged from loamy fine sands to clay loams with slopes shown by walking over the plots after the rainfall had ranging from 0.3 to 9%. stopped. Dramatic differences among treatments were Runoff and erosion were consistent across treatments for observed by the depth the person sank into the soil. On most all sites. During most demonstrations, no runoff was gener- sites, a person could walk on top of the bare soil plots imme- ated from any of the residue plots with more than 80% diately following the demonstration. On the plots with high- er crop residue cover, the person would sink up to 15 cm (6 in) into the soil. This was a convincing illustration of the effectiveness of crop residue cover in increasing infiltration. The program received extensive coverage in the media. Numerous radio and television interviews were conducted and the local newspapers usually covered the demonstration on the front page. A 12-min video was produced in 1994 featuring the rainfall simulator (Kok et al., 1994). Water conservation, infiltration, runoff, and erosion are discussed in this video much like during the actual demonstrations. The tape also addresses conservation compliance, crop rota- tion, tillage systems, soil productivity, and water quality Fig. 2. Shown are PVC tubes to demonstrate splash erosion. Note soil issues. A 3-min video clip explaining the water conservation splashed on tube not surrounded with crop residue. education educational program was produced for use by

22 J. Nat Resour. Life Sci. Educ., Vol. 26, no. 1, 1997 television stations. Several stations broadcast this clip dur- ing prime time news programs. ACKNOWLEDGMENTS In 1992, a written survey was conducted among agricul- tural producers and agency personnel attending the demon- The authors thank the many people who helped with the strations. Of 305 surveys distributed, 40% were returned. rainfall simulator demonstrations. We thank Phil Barnes, The majority of respondents, 95%, rated the program as agricultural engineer, Kansas River Valley Experiment "worth their time," and 60% said they would "come back to Field, Kansas State University, designer and construction see the demonstration again." In addition to the audience supervisor of the Kansas State University Rainfall comments made at the demonstrations, many positive com- Simulator; and Paul Jasa, extension engineer, Department of ments were written on the survey sheets, indicating the pro- Biological Systems Engineering, University of Nebraska, gram was highly appreciated. Lincoln for helping with the 1992 demonstrations, and sug- gestions on construction of the KSU simulator. The KSU- The producers were asked if they would change their farming practices after seeing the demonstration. More than CES and AES provided the funds for the construction. Also, 40% said they would, and another 40% indicated they may. we thank the Kansas State University Water Quality Fund The majority of producers indicating they would change and the Natural Resources Conservation Service in Kansas their practices stated that less tillage (34% of respondents), for providing funding for student labor in 1992 and 1993, and leaving more crop residue on the soil surface (33%) respectively, and Majory Mortvedt, Office of Planning and Reporting, for processing the 1992 survey. would be their goals. A small percentage of the respondents (9%) said they thought they were already doing enough for erosion control. The response to whether their neighbors had erosion was much more convincing: 79% said their neigh- bors had erosion on their land, whereas 20% said their neighbors had "some" erosion. Less than 1% thought their neighbors had no erosion. The survey asked for wheat yields and the number of tillage operations performed before the next crop was plant- ed or drilled. Producers were asked to estimate the amount of crop residue left on the soil surface after planting this next crop. Most respondents overestimated this amount, com- pared with estimates produced with the RES-N-TILL1 (Kok and Thien, 1994) residue management software and field observations. The survey showed that farmers in western Kansas were more aware of the residue levels in their fields than farmers elsewhere in Kansas. Western Kansas farmers reported residue levels in their fields (20-30% cover) close to, or even lower than the calculated estimates (25-50% cover). The other farmers overestimated this amount by as much as 100% (10—50% cover range) compared with the calculated values (10-40% cover).

CONCLUSION A rainfall simulator demonstration is a powerful tool to promote water conservation, by showing water infiltration, water runoff, and soil erosion. The demonstrations make a good background for discussion of issues such as water con- servation, crop rotation, and conservation tillage practices. The program has raised awareness of water conservation, erosion, and conservation compliance in Kansas. Farming practices are changing partly as a result of this program.

1 Mention of a trade name does not imply indorsement by the authors over similar products not mentioned.

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