1974 RESEARCH REPORT. 4:pp. KA ( L.(4. csc5v, Oregon's Drip lrrigati tet-4z. Special Report 444 November 1975

Transcription

1 KA ( L(4 t?a 719t w \(,) c csc5v, Oregon's Drip lrrigati tet-4z 1974 RESEARCH REPORT Special Report 444 November 1975 Agricultural Experiment Station Oregon State UniTsity,,Corvallis Awka A icsr;"zie 4t-v4 itr4 4:pp =

2 FOREWORD Drip (trickle) irrigation is a method of applying water to individual plants at a low rate from a network of small pipes, tubes, and emitters Water moves from the discharge points, largely through capillary movement, to plant root systems Soil moisture content varies considerably between locations in root zones but is relatively constant at specific locations throughout the growing season when compared to variations in soil moisture under other methods of irrigation Because of the complete control of water during irrigation, this technique potentially offers considerable opportunities for water savings, labor savings, and the benefits derived from precise soil moisture control Drip irrigation was first introduced to the United States from Israel for use in agriculture within the last six years Many questions relating to crop adaptability, design, scheduling, and system conversions need to be answered for the development of sound recommendations of its use This report summarizes results of the second year of research projects on drip irrigation in Oregon This work was conducted at the Mid-Columbia, North Willamette, and Southern Oregon Experiment Stations in cooperation with the Agricultural Engineering Department For additional information, contact Marvin Shearer, Extension Irrigation Specialist, Department of Agricultural Engineering, who edited this report, or any of the other authors AUTHORS: Marvin N Shearer, Professor of Agricultural Engineering; Dr Porter B Lombard, Walter M Mellenthin, Dr Lloyd W Martin, Professors of Horticulture and Superintendents of the Southern Oregon, Mid-Columbia and North Willamette Experiment Stations respectively; C Y Wang, Research Associate; and Scott Kelly, Research Assistant; all of Oregon State University

3 ABSTRACT Two years data on drip irrigation systems operating in mature pears, apples, and blackberries indicate the K value relating water loss from class A evaporation pans to irrigation requirements was approximately 10 when applied to the area under the plant canopy Tensiometers were used to moniter soil moisture and identify refinements needed in scheduling programs For the second year, there was no significant difference in the occurrence of fruit mold on sprinkler and drip irrigated evergreen blackberries Water savings with drip irrigation compared to furrow irrigation in mature pears with partial ground cover ranged from 10 to 0 percent; with drip irrigation compared to sprinkler irrigation in mature pears with complete ground cover, the saving was 45 percent; with drip irrigation compared to sprinkler irrigation on six-year old evergreen balckberries, the saving was 33 percent Drip irrigated blackberries matured earlier than those sprinkler irrigated with no observable detrimental effects in yield or quality Drip irrigated Bartlett pears reached comparable maturity one week earlier than those furrow irrigated At harvest, drip irrigated pears were slightly larger but 5 percent were over-mature CONTENTS 1 A Comparison of Two Drip Irrigation Schedules with Sprinkler Irrigation in Thornless Evergreen Blackberries 1 Scheduling Drip Irrigation with Evaporation Pans 5 3 Drip Irrigation Progress Report in the Mid-Columbia Area 9 4 Pear Tree Response to Drip Irrigation on Carney Clay Soil, Second Season,

4 A COMPARISON OF TWO DRIP IRRIGATION SCHEDULES WITH SPRINKLER IRRIGATION IN THORNLESS EVERGREEN BLACKBERRIES Lloyd W Martin and Marvin N Shearer Drip irrigation has been studied in Thornless Evergreen blackberries at the North Willamette Experiment Station since 197 In 1973, one drip irrigation schedule, based on class A pan evaporation data, was compared with conventional sprinkler application Yield was reduced in the drip treatment, apparently because of inadequacies in the method of scheduling water applications In 1974, two drip irrigation schedules which were modified monthly to compensate for the increased plant growth were evaluated The 1974 data are presented from the drip irrigation plots and compared with data from the sprinkler irrigated plots Procedure The area that had been previously drip irrigated was divided into two main plots composed of 5 replicates each Individual plots were single rows, composed of 8 plants spaced 5 feet apart The size and location of the sprinkler plots remained the same as previously reported Two water application schedules, based on evaporation from a class A pan, were evaluated in the drip system, K=10 and K=1 The amount of water to apply was calculated by the following formula: Gallons of water per plant = K x E x A x K = 1 or 10 E = inches of evaporation since last irrigation A = surface area beneath plant calculated by multiplying row width as measured at the first of each month times feet between plants Intervals between drip irrigation applications varied from three to six days The water application schedule in the sprinkler plots was designed to apply one inch of water per week, minus rainfall, during May and June and one and one-half inches per week from July to the end of harvest Applications were made on a 5 to 10-day interval Soil moisture was monitored with tensiometers at 1, 4, and 36-inch depths at three stations approximately 1 inches from emitters in each of the three main plots Emitters were located in the row approximately 1 inches from the crown of each plant Tensiometer readings were recorded at about 8:30 am daily throughout the growing season

5 Ripe berries were hand picked on four dates in August and September Twenty-five ripe fruit were selected at random from each of the plots at the last harvest, kept at approximately 68 F for 10 days, and visually checked for the presence of gray mold rot, Botrytis cinerea The canes that had fruited were pruned out after harvest and the remaining primocanes counted and measured Results and Discussion Some notable differences in soil moisture occurred between the 3 irrigation treatments (Figures 1, and 3) The soil moisture in the drip irrigation plots was approximately the same until about August 1 At,that point, the soil moisture suction at the 1-inch depth in the K=10 plot began to increase, exceeding 50 centibars (cb) on August 8 However,moisture at the 4 and 36- inch depths remained about the same, in the 5 to 0 cb range, until the end of harvest 1, 00' ' ' ; ' 7' ' I ''' LLLi : '' $ SOIL - i - I t -! SUCTION - - -, - 1 i C I : -, II H-H--rk't=''' 1- Cb: 0 1 _ I _ " - :st [ : - -I _ A Alli Ad& _ i _, V liairw afiggiarill_mm 41 - ikiiimmuimaina malcall:mmom ' I" 'i: 4-,, ---- ' 1 H _ ! MAY JUNE JULY AUGUST SEPTEN3ER Figure 1 Tensiometer readings for drip irrigated blackberries, average of 3 stations (Irrigation = Pan Evaporation x 10) Figure Tensiometer readings for drip irrigated blackberries, average of 3 stations (Irrigation = Pan Evaporation x 1)

6 MAY JUNE Figure 3 Tensiometer readings for sprinkler irrigated blackberries, average of 3 stations, 1974 JULY Greater variations in moisture, at each of the depths measured, were evident in the sprinkler plots (Figure 3) From June 13 to July 5, soil suction at the 1-inch depth remained relatively high, ranging from 30 to 70 cb Moisture suction at the 4 and 36-inch depths was approximately the same during this period; both increased from about 17 to 40 cb Following a one-inch rain July 8, soil moisture suction dropped to 0 cb or less at each of the three depths From July 10 to August 1, suction again increased at each of the depths to a high of 40 to 60 cb Following a heavy irrigation August 1 of 86 gallons of water per plant, suction at the 1 and 4-inch depths dropped to below 10 cb then gradually increased until the end of harvest Tensiometer readings at the 36-inch depth remained relatively constant during this period, ranging from 35 to 50 cb Yield and fruit size were not significantly different between treatments at the 1 percent level (Table 1) However, plots receiving drip irrigation matured fruit earlier in the season and produced significantly more fruit the first harvest than those sprinkler irrigated The variation in moisture and/or the brief periods of higher soil moisture suction in the sprinkler area apparently delayed ripening This is of practical significance since labor for hand harvest is more difficult to get later in the season and also the probability of rains disrupting harvest is greater Table 1 Effect of irrigation system on Thornless Evergreen blackberry yield and fruit size, North Willamette Station, 1974 Drip (K=10) Drip (K=1) Sprinkler Average Yield (lb/plot) First Harvest A/ Total b/ Size (g/berry) a/ harvest yields between sprinkler plots and either of the drip plots were significantly different at the 1 percent level I)/ Total yield between sprinkler plots and the drip (K=1) was significantly different at the 5 percent level

7 It is generally believed that fruit rot should be less under the drip system than the sprinkler system; however, the difference was not significant after holding the fruit for 10 days (Table ) None of the plots were measureably infected with fruit rot at time of harvest Table Effect of irrigation systems on fruit rot of Thornless Evergreen blackberries Drip (K=10) 19 % of fruit infected/ Drip (K=1) 160 Sprinkler 0!/Ripe fruit held 10 days at 68 F Growth of new canes was not differentially affected by the systems of irrigation (Table 3) Diameter of canes averaged just over 1/ inch and ranged in length from 137 to 167 feet Number of canes per hill ranged from 40 to 49 Table 3 Effect of irrigation systems on cane growth of Thornless Evergreen blackberries Cane length (ft) Diameter (1/16 inch) No of canes per hill Drip (K=10) Drip (K=1) Sprinkler

8 ' SCHEDULING DRIP IRRIGATION WITH EVAPORATION PANS Marvin N Shearer The technique of determining irrigation schedules from pan evaporation described in "Drip Irrigation Research in Oregon," Special Report 41, published in 1973 by OSU Agricultural Experiment Station,was examined in more detail at the Southern Oregon and North Willamette Experiment Stations in 1974 Discussion Tensiometer readings taken under a Bosc pear tree of 195 feet mean diameter, a Bartlett pear tree of 185 feet mean diameter, and another Bartlett of 165 feet mean diameter are shown in Figure 1 From these data it was concluded that the Bosc was under irrigated, the larger Bartlett was adequately or slightly under irrigated and the smaller Bartlett was adequately or slightly over irrigated to C' i; ' [-- - I - I--4- ' - BOSC ft dia - c i - I I ' : I - t -; i ; ' " ' r---i, i ; 1 i I - SOIL '71- _ 1" 1,_,i,,,tten7V; -'r---- ;;,1-,,", ),--, SUCTION, 4" I dal :, - i -- Iftealia, > " -: Cb --tv i--:;[--;!--1-;11" i / % ; I >t: 7'I 1' I I iiii A I' '' El ' ' h- -- 1: 1111 IVA ,-7-,--\--:- 1-1 : ; -i i 3 1: A S 10 IS 3 MAY JUNE JULY AUGUST SEPTE113E4 SOIL 1" SUCTION, -- 4" -7 : Cb >rt 36" -' ' --- '' r - I' ", r, 1, - _1 ;!_i BARTLETT ft dia I I I - I! -! 1 " ' i - I': - ' ' - I 7! V -1,:ar ' i,_ --k,,,,,4,4,,,, ',,, [ '"'-1/ \+-""'"v"F V I' 1 -" Al \P 11- i 1i i I - - _ I ) : i : / I : IAV; I 1 H ' - ' I i - ; [i - : 1 ' _ 1 H " ---1-:',1--', :77;-7- :,,, 0,; 1 ; ; I I I '-, - - :- i- -I -A' --",;-, ----,, ; -9,--4-1, : V,- 6,,, 1 1!1 4 ' i - : ' - *1- -, t i t ' -L4,-"_-:, / a-?atli ;44;:: S MAY JUNE JULY AUGUST SEPTEn3ER to - - -,-- SOIL a - SUCTION, Cb 4 r - --, I ' :' i II i L BARTLETT ft dia ' ' 10 -"LD i i = 1 1" - - i--i 4" ' '-- r -t iorvesi --i-1 I 6C 6" i 1 1 ' 3 v IN --1, ' 1, -(1,-0- :1 4C _ A :DLLi 11--i--- A-1;, : , 1I 74iir,1_ I -- r - ' 1,1 : r-i-44_1:; I Tr* le' ; 1) 0-1(1-,,,i i: i ry 14-14, r, 0 - : :: ' 1E,,, ili ii, N I' 1-1:I-v t AL -47 -,: 0 ' -CV,, 1 0 IS nn M5 W n IS S MAY JUNE JULY AUGUST SEPTEM3ER Figure 1 Tensiometer readings under three different diameter pear trees, Medford, Oregon,

9 Figure shows a comparison of the water applied to the calculated water required for drip irrigated trees of the three diameters when a K value of 10 was used to relate Class A pan evaporation to irrigation requirements An evaluation of Figures 1 and shows the irrigation requirements could be approximated by applying evaporation pan measurements to the area under the tree canopy, using a K value of 1, to determine the quantity of water applied per tree per irrigation (ie, irrigation requirements = evap x 10x area under canopy) 6000 WATER IN GA/TREE / % / / /,/// Water applied ---- Water required, 195 dia tree --- Water required, 185 dia tree ----Water required, 165 dia tree 0 t May June July August September DATE Figure Comparison of water applied to calculated water required for trees, based on Class A evaporation pan measurements These findings, however, suggest the importance of selecting "representative" trees or tensiometer stations for estimating timing and duration of irrigations and field observations of soil and crops There was approximately a 30 percent difference in calculated water requirements due to canopy diameters During May and June, the Bosc tree was used as a guide because of water penetration problems encountered in 1973 Even though both the tensiometer readings in Figure 1 and the "required-applied" comparison in Figure show the 195 foot diameter Bosc tree was removing more water from the soil than was being applied, (on a daily basis) the trees showed "wet feet" symptoms (See discussion by Porter Lombard in this report) Corrective measures were taken near the end of June and the fruit produced compared favorably with that which was furrow irrigated Tensiometer readings from the furrow irrigated plots are shown in Figure 3 6

10 ,, 10! i i L FURROW- BOSC - I - ' I- I I 1 I 1-7 SOIL 8 /-6 - ',, ` --1 t i=--, 8Z " - 4" 1-7"77:711/7 SUCTION6,,, --;,-,4:5;-- i i - t - -t 7, " 1----; Cb i,, Igar'yesf-p :,, i r ! -: : --i- i 4 i',, _ - L t - " - ' ; I - r i 1-1 ' :,, I r r, 1 t I MAY JUNE JULY AUGUST SEPTE713E14 SOIL e SUCTION6 Cb 10 1 ' ' ' '' -i I i, 1, 1" FURROW - BARTLETT : - I* -I' I --7 I 1 4 ' *- --"I''''7"" I I j i-: ---,- J, i,,,, so _ ftei i I " ; r 1 4, fa I A7eqf fi/f+1 6C i; 1-171,,_ --e;',1--1? ;;;;;i-71'i - 14v ; ;,, - '; 4 0 C't, 1!; : I i -! -; :1 1-1/ I- *-Harveif - :! r - I ' ' [ ' I T ' I, _1_ 1-: I i ; i :- i !-- t to t S : MAY JUNE JULY AUGUST SEPTENZER Figure 3 Tensiometer readings, furrow plots, Medford, Oregon, 1974 At the North Willamette Station, Class A pan evaporation data were adjusted with K values of 10 and 1 for scheduling irrigations and applied to an expanding canopy area Yields were 8 to 9 tons per acre which were considered excellent It was assumed, therefore, that water was not limiting in any treatment Tensiometer readings are shown in Figure 4 From these data it was concluded that K = 1 resulted in over irrigation and K = 10 resulted in good soil moisture conditions SC!L EIC;, ttt, tt I I K = 10 t"" I i- SUCTION,cL 1" I 6, Cb 4" I - 1L 71ILL - -+"" I -- - I " _ 4 re I-, _ I I, t 7 : ; ; ; ; I t I I - r I 0 : IS i MAY JUNE JULY AUGUST SEPT 3:t3ER 86 +! 1! H _4 L t ;, 1,,,,, ' SOIL h-- ; :-3 SUCTION 6 L LJ- ' K = 1 ' 1---'-- l_c_c_iii I ' (:J----i f- - L ' 'l 1 r i : i , 1 -!-- ;-; I i Cb,-- I 1" C -- 4" I I 7 I 7 - [ 7 7 ' IT ' _±71 - ' I - "'HI' - i '1 6 4o-- 36" 1 -- ';'- ' - '1" :- ---, :-L--FTI--i----I-1 I, 1:::: I 177 _:i I 1 1 i F *1 ;"` r ,, r _ Li I 1 ---I ; 1,- 1 1 i _ i i 771 L-' i,-j-7- --,--71 ;--, I 1 i I ' i_a,_, 17 FI- 113 T,,-,-- --T t,! :-7-:-:-T:;-13;;;_;±vV:i?---vi-,y- --,? : - - A ', to J ' :- -11"C"'" -I " - ' :, --1-!! I 0 i :0 MAY JUNE JULY AUGUST SEPT:EN:3ER Figure 4 Tensiometer readings for drip irrigated blackberries, average of 3 stations for each treatment 7

11 Conclusions It was concluded from the orchard and cane berry tests that the procedure described in Special Report 41 for using Class A evaporation pan data and a K Value of 10 to determine irrigation requirements appears to be sound but soil moisture should be monitored for determining the need for minor adjustments in the irrigation program

12 DRIP IRRIGATION PROGRESS REPORT IN THE MID-COLUMBIA AREA W M Mellenthin, C Y Wang, S B Kelly Studies relative to the use of drip irrigation in mature pear trees (Anjous and Bartletts) were continued in 1974 Results from 1973 showed a decrease in the percent of No 1 Bartlett pears for the drip irrigated plots compared with the sprinkler irrigated plots With the winter pear variety (Anjou) there was a slight increase in premium sizes (90-135) in favor of the drip system - over conventional sprinklers Since the 1973 data were for the first year of this study it is possible that slight differences in fruit sizing were due to the transition from sprinkler to drip irrigation on established pear plantings The 1974 sprinkler plot irrigation scheduling was based on tensiometer readings shown in Figure 1 Only two irrigations were required for the Bartlett variety; three irrigations were necessary for the later maturing Anjou variety A comparison of water application between sprinklers and drip methods is shown in Table 1 to sat SUCTION6 Cb 4 _ " 1---/ H I ; : - 1, "--- --r _ ir :1-'7" SO O r- e, -?- - I : 1-F -- ' i --'- 5 0 i IS 0 JUNE JULY AUGUST SEPTEMBER 0 Figure 1 Tensiometer readings for sprinkler irrigated Anjou and Bartlett plots, 1974 Table 1 Comparison of water application on sprinkler and drip irrigated pear plots, 1974 Av Annual Application No of No Emitters Inches Precipitation Variety Method Irrigations Per Tree Applied 6/1 to 9/30 Bartlett Sprinkler Anjou Sprinkler Bartlett Drip 74 6 Anjou Drip

13 The influence of drip irrigation on tensiometer readings for Bartlett and Anjou pears is shown in Figure I 5 0 IS to JUNE JULY AUGUST SEPTEMBER Figure Tensiometer readings for drip irrigated Anjou and Bartlett plots, 1974 Water applications through the drip system as described in Agricultural Experiment Station Special Report 41 were continued in 1974 A comparison of cumulative weekly fruit growth between sprinkler and drip irrigated Anjou pears is shown in Figure 3 Each emitter was calibrated for 094 gallons of water per hour Hence, the -emitter trees received 188 gal/hr; 3-emitter trees received 8 gal/hr, and 4-emitter trees received 376 gal/hr Emitters Emitters 4 Emitters S----5 Spri nk 1 /$ s ) o June i I I July August Sept Figure 3 Fruit growth as influenced by irrigation method and treatments The effect of irrigation treatments on Bartlett sizes and yields is shown in Table The data show there was no difference in average yield per tree between the sprinkler plots and the -emitter per tree drip plots Pressure tests showed no significant difference in maturity There was, however, a 7 percent increase in the yield of No 1 pears and a 46 percent decrease in No 's 10

14 Table Influence of irrigation treatments on Bartlett Pear sizes and yields, 1974 Sprinkler Drip* No 1 No Cull No 1 No Cull Size Range Av Yield/Tree (lb) 557 lbs 559 lbs Range lbs lbs Firmness (harvest) 187 lbs 189 lbs * emitters per tree Table 3 shows the percent packable Anjou fruits in various sizes as affected by different drip application treatments These data indicate that as long as there was a consistent moisture supply, the percent of premium sizes (90-135) was not increased by increasing the amount of supplemental water through the drip system There was, however, a considerable difference in the percent premium sizes between the drip systems and the sprinkler plot Table 3 Influence of irrigation treatments on Anjou Fruit size Packable fruit (US l's & Fancy's) Drip Emitters per tree Grade Sprinkler 3 4 % % % % 80 & Larger & Smaller Culls Soil samples were taken July 3, August 7, September 3, in a 1-foot grid pattern outward from the emitter as shown in Table 4 Soil moisture was maintained under all emitter arrangements at a relative uniform moisture level at the 4-inch depth to a distance of about 4 feet from each from July 3 to August 7 but considerable reduction was measured at that depth 6 weeks later as close as to 3 feet from the emitter 11

15 Table 4 Soil moisture distribution under tree irrigated with emitters, in percent moisture, 1974 Distance Outward From Emitter Depth Date 6" 18" 30" 4" 54" 60" Inches % % % % % % July Aug Sept July Aug Sept July Aug Sept The drip irrigation system used in this study by the Mid-Columbia Experiment Station was previously described in Special Report 41 Plugging of micro tube emitters was not a problem because of an adequate filtering and flushing program There was, however, considerable labor used in calibrating the micro tubes at the start of each irrigation season because of flow rate changes observed when the system was turned on in the spring 1

16 PEAR TREE RESPONSE TO DRIP IRRIGATION ON CARNEY CLAY SOIL SECOND SEASON 1974 Porter B Lombard Drip Irrigation Regime Tensiometers were used during most of the season to determine the frequency and amount of drip irrigation after first trying daily irrigations based on daily evaporation Daily irrigations kept a substantial portion of the soil under the canopy near saturation because of the frequent irrigations Several weeks after drip irrigation had started, tree foliage showed considerable leaf marginal burning It was then decided to switch to tensiometers to determine when and how long drip irrigation systems should operate The 4-inch tensiometer area was allowed to reach a suction of 10-0 centibars before irrigation was started The irrigation was continued until all the 1 and 4-inch tensiometers in Bartletts dropped to zero The appearance of the trees improved under the new irrigation regime, probably because of improved soil aeration It was concluded, therefore, that scheduling of drip irrigation on clay soils should be determined by specified reading of tensiometers placed 1-18 inches from the southwest emitter and daily irrigations should not be followed (See detailed discussion in report on Scheduling Drip Irrigation) Soil depth of drip irrigation on clay soils No soil moisture withdrawal pattern survey by soil sampling was made in 1974 as was done in 1973, but tensiometers indicated deeper water penetration from irrigations in 1974 Seldom did the wetting front reach 4 inches depth in 1973, but the front was generally at or below 4 inches following an irrigation in 1974 Drip vs furrow irrigation of pear trees on clay soils Irrigation water applied by the drip system was 8 and 9 percent of the amount applied through furrows The reduction of seasonal water use by drip was partially due to the absence of runoff which is an important consideration for irrigation districts currently faced with return flow restrictions The value of water saved by drip systems operating in mature trees in the Medford area is not of economic significance Response of pear trees to drip irrigation compared with furrow irrigation showed no large differences Rate of fruit growth was greater for furrow irrigation but harvest fruit sizes of Bartletts were larger under drip irrigation This apparent contradiction was also observed in 1973 Five selected fruits of uniform initial size were measured on 4 trees under each treatment (total of 40 fruit) for rate of growth measurements One hundred pears from four trees under each treatment (total 800 fruit) were randomly-selected for making harvest size comparisions (Table 1) 13

17 Interaction of fruit maturity and method of irrigation was noted only on fruit pressures of Bartletts during harvest (Table ) Lower fruit pressures of Bartletts under drip irrigation could produce considerable ripening on the tree during a cool season which can have a deletrious effect Therefore, no particular advantage in fruit response was found for drip irrigation of mature pear trees in the Medford area The advantage of larger Bartlett fruit was probably balanced with the disadvantage of early fruit ripening on the tree Table 1 Effect of irrigation treatment on fruit size, Medford, Oregon, 1974 Irrigation % greater Method than 3/8 inches drip furrow Ave Dia in inches wt/fruit lbs % rotted fruit Bartlett Bartlett Bosc Bartlett Bosc Bartlett Significance level NS 5% NS 5% NS Date Variety Table Effect of irrigation treatment on maturity of pears, Medford, Oregon, 1974 USDA Press Test Signif Soluble Solids Drip Furrow level Drip Furrow lbs lbs Signif level Aug 0 Bartlett MS N S NS NS N S % Sept % N S Sept 6 Bosc NS NS NS NS NS NS 14