TDOC Z TA245.7 B873 NO.1659 ' B - r659 October i990 nut Profits rrigation Yield Response the Northern Texas High Plains - Non-Traditional Production Area Texas Agricultural Experiment Station - Charles J. Arntzen, Director - The Texas A&M University System - College Station, Texas m mus MM lmwlaasm UBR '3 v .. if ,... [Blank Page in ongm Bulletin] l r .-.2 w‘ ‘ . a.’ * s .15. \ K ,\ \ , ‘~21 8-1659 Peanut Profits and Irrigation Yield Response in the Northern Texas High Plains, A Non-Traditional Production Area Wyatte L. Harman, C. Regier, F. Petr and V.D. Lansford* * Respectively, agricultural economist, research scientist-in-charge, Texas Agricultural Experiment Station, Amarillo, Texas; Emeritus extension agronomist, Texas Agricultural Extension Service, Amarillo, Texas; and research associate, Department of Agricultural Economics, Texas A&M University, College Station, Texas. [Blank Page in 0 . ' etiq ~ 3%‘ u- is. ‘s §j,_,.,/5;1;/@-rt,sej1aa@ 0d Summary Investigation of surface (furrow) irrigation and timing of applications in relation to peanut yields in a non-traditional growing region, the northern Texas High Plains, indicated profitable grades and produc- tion levels of selected spanish and valencia cultivars could be attained within the area's short growing season. Irrigation rates during the growing season, which maximized profits, were nearly 26 inches for Pronto (spanish) and 23 inches for McRan (valencia). With these irrigation levels, estimated yields from mul- tivariate water-yield response functions were 4,018 and 4,443 lb/ ac, respectively. Profit-rnaximizing levels of seasonal irrigation were relatively insensitive to wide variations in peanut prices ($0.10 to $0.35/lb) and ir- rigation costs ($2 to $6/ in). Analysis of eight alternative irrigation timings (in addition to an irrigation at bloom stage) indicated an early application 21 days after planting and several mid- to late- season irrigations were significant in deter- mining peanut yields. Moderate to heavy rainfall in September and early October would reduce yields of McRan on moderately permeable soils. Grades of Pron- to were not significantly affected by the number of irrigation applications ranging from two to seven, but a moderate (four irrigations) to high (seven irrigations) number of applications were needed to assure maturity and maintain high grades of McRan. With average rainfall, returns to management and risk were $821/ ac for McRan and $673/ ac for Pronto. In this case, nonquota prices would need to be about $311/ ton for Pronto and $277/ ton for McRan to break even with total production costs. Season-long below average monthly rainfall approaching that of the modal frequency (40 percent of average) would reduce yields about 200 lb/ ac and profits by nearly $60/ ac. More commonly, a monthly rainfall deficit, such as July, of 40 percent of average, would reduce Pronto yields over 90 lb / ac and McRan, over 180 lb / ac, and profits by $28 and $54 / ac, respectively. Introduction The Texas High Plains is characterized by a relatively short frost-free season ranging from as little as 180 days in the northwest to 220 days in the south (Bonnen, 1960). The semi-arid climate of 16 to 20 inches annual rainfall requires irrigation for crops with high water require- ments. Profits from irrigated crops adapted to the region have generally been declining since the mid- 1970s due to high pumping costs and declining crop prices. 1989 estimates‘ of returns to management and risk for the major irrigated crops wheat, corn, sorghum, and cotton were $20.55, $91.43, $42.81 and $9.14/ ac, respectively (Texas Agricultural Extension Service 1989a and b). These narrow profit margins have renewed producer interest in alternative crops. While the region is climatically suited for producing several alternative crops, readily available markets for these crops may be limited. Also, specialized machinery and management skills may be required. One of the more profitable crops grown in the southernmost portion of the Texas High Plains and central Texas is peanut. Estimated returns to manage- ment and risk in the High Plains range from $339/ ac to $580/ ac depending on the type of peanut (Texas Agricultural Extension Service, 1989a). Breakeven prices range from $326/ ton for spanish peanut (used primarily for crushing) with an estimated yield of 3,500 lb/ ac to $262/ ton for the runner type (used for confec- tion, roasting, and crushing) yielding 4,500 lb/ ac. Objectives The above breakeven prices and profit levels were estimated using a high level of irrigation for peanuts. Estimates of peanut yield response to alternative levels of irrigation are needed to provide an improved economic basis for determining the maximum profit (optimum) level of irrigation. Knowledge of the most profitable timings of applications relative to physiologi- cal development and yield response is important also for efficient use of water resources. Thus, the objectives of this research were to (1) assess peanut yield response to surface (furrow) irrigation as an alternative crop in the northern Texas High Plains, and (2) evaluate the profitability of peanut production in this non-tradi- tional short-growing-season region. Review of Literature Newman (1979) and Bausch et al. (1971) found that early season plant water stress delayed blooming as well as maturity, reduced vegetative growth, and resulted in lower yields. Newman indicated stress at the bloom stage at Stephenville, Texas, where the frost- free period is nearly 240 days, could delay maturity 15 percent which could be critical for some late maturing spanish and runner varieties. Hiler et al. (1970) reported frequent, light water applications were superior to in- frequent, heavy applications. In further studies in 1975, when seasonal rainfall was only 35 percent of normal, Newman and Roberson (1976) found that frequent ir- rigations on a 4-day interval caused plant leaf yellowing as a result of excessive moisture. Average yields of 7 varieties were reduced more than 20 percent compared with the highest yielding irrigation interval of 8 days. Others have found that water stress was more critical during pod set and pod formation in contrast to stress at earlier stages of physiological development (Stansell and Pallas, 1985; An, 1978; Reddi and Reddy, 1977). Furthermore, excessive late season irrigations or rain- fall, especially on heavier soils, can decrease yields (Mantell and Goldin, 1964). Peg attachments may be weakened and disease incidence may increase, result- ing in higher harvesting losses through detached pods. However, if soil moisture conditions are extremely dry at harvest, the digging procedure may be more difficult (Newman, 1979). _ While much of the previous research was located in areas having sufficient growing season for peanut maturity, little is known regarding attainable peanut yields and the yield response to irrigation outside tradi- tional peanut production areas, where a relatively short growing season may influence seed quality and yields. Methods and Procedures The research was conducted at a fann site near the Texas Agricultural Experiment Station North Plains Research Field, Etter, Texas, on a Dalhart fine sandy loam soil (Alfisol, Aridic Haplustalf). This soil is char- acterized by a fine sandy loam layer from 0 to 9 inches in depth, a sandy clay of 52 inches depth, sandy clay loam to varying depths of around 6 to 7 feet, and a highly calcareous layer below. Soil permeability is moderate and available water capacity high. The soil typically has a pH ranging from 7.5 to 8.0. Peanut irrigation research was conducted at the farm site for 4 years, 1983-1986. A randomized complete block experimental design was used to evaluate four alternative irrigation levels each year. Two peanut types, spanish and valencia, consisting of two single 40-in rows each were evaluated in two adjacent sub- plots in each irrigation plot. Relatively early maturing cultivars were evaluated including 'Pronto’, a spanish type, and ’McRan’, a valencia type. Three replications were evaluated for each of 16 irrigation treatments of each cultivar. Irrigation plots were 13 1/3 ft wide and ranged from 200 to 300 ft in length over the years. Main plots were separated by two rows of unirrigated cotton to prevent interaction of irrigation applications. Cul- tivar subplots were located 80 ft from the beginning of the furrow run and were 6 2/ 3 ft wide (two 40-in rows) by 30 ft to 36 ft in length over the years. Planting dates were about May 20 and the seeding rate was 80 lb/ ac. Prior to planting, plots were uniformly irrigated after incorporating 0.75 lb/ ac tri- fluralin [2, 6—dinitro-N, N -dipropyl-4-(trifluoromethyl) benzamine]. Nitrogen (N) and phosphorous (P) fer- tilizer applications varied by year and plot location. Adequate rates were applied to prevent N and P from limiting production based on soil nutrient analysis. Insects such as thrips were controlled as needed. No diseases were encountered, but plots were moved each year to a new location that had no history of peanut production. The preceding crop was either irrigated or dryland wheat at each location. Irrigation treatments consisted of alternative timings and amounts on graded furrows. In 1983, two to five seasonal irrigations were applied whereas in following years five to seven irrigations were evaluated. All irriga- tion treatments received an irrigation at early bloom (about 42 days after planting) while other applications were varied at days after planting of 21, 56, 63, 70, 77, 84, 98, and 112. Net water applications for the growing season (excluding preplant irrigation) ranged from a low of 8 inches to a high of 29 inches. Net water applica- tion amounts were determined as the difference be- tween gross applications measured with in-line water meters and plot runoff measured by H-flumes equipped with stage recorders. Deep percolation losses were inconsequential due to the short irrigation run and nominal net amounts measured relative to the soil water holding capacity. Cultivar yields were obtained from 13-ft sections of the rows nearest the middle of the main irrigation plot. Plants were undercut with a blade in early October and hand-harvested. Yield samples were threshed and oven-dried. Yields were expressed as 12 percent seed moisture. Grades for irrigation treatments and cultivars were determined from composite samples of the three replications. Yield response to varying levels of seasonal irriga- tion amounts, timings of application, and seasonal precipitation was analyzed by ordinary least squares (SAS, 1985). Forty-eight yield observations of each cul- tivar (3 replications x 16 treatments) were used in the analysis. Significant differences between grades were assessed by Duncan's multiple range test. Results The following discussion presents (1) two peanut water-yield response functions for Pronto and McRan, (2) water-yield response functions relating significant irrigation applications, other than at bloom, (3) quality impacts of irrigation applications on grades, and (4) economic implications regarding both the maximum profit levels of irrigation with varying water costs and peanut prices and the potential profitability of produc- ing each of the cultivars in the northern Texas High Plains. Water-yield Response Function, Pronto Cultivar Yields of Pronto were significantly related to seasonal irrigation levels and rainfall variables. The following r lationship explained 84 percent of the variation (R =0.843) in yields: (1) YP = -649.84 + 6.994 12 - 0.1855 13 + 8.5036 (PJUN) [348.1] [3.01] [0.10] [$5.99] (-1.87) (2.32) (1.85) (2.13) +690.15 IAS - 41.937 (]AS)2 [1710] [1520] (4.04) (2.76) R2 = 0.843 F = 44.94 n=48 where YP = in-shell yield of Pronto peanut (lb/ ac), I = seasonal irrigation (in), IUN = June precipitation (in), I*]UN=Interaction of seasonal irrigation x June precipitation (in), and IAS = total July + August + Sep- tember precipitation (in). % #4 ~¢ x/ Brackets include standard error of the estimates and the parentheses contain the T-values of the coefficients. All regression coefficients were significanst at the 4 per- cent level of significance or less except I , which was significant at the 7 percent level. The F-value was sig- nificant at P = 0.0001. Forty-eight observations were used (n). Figure 1 and Table 1 indicate estimated yields (total physical product or TPP) of Pronto for seasonal irriga- tion levels (excluding preplant irrigation) ranging from I=0 to 30 inches. TPP was based on monthly average rainfall for a 26-year record at the North Plains Research Field, Etter, Texas. June rainfall (JUN variable) averaged 2.61 in and July + August + September rainfall (IAS variable) averaged 5.96 in. Stages of economic production are also indicated in Figure 1. Stage I of economic production indicates the range of irrigation over which average physical product (APP) increases to a maximum. Profits are not yet max- imized over this stage since APP increases as water increases. In Stage II, however, APP decreases as water increases and, at some point within Stage II, the in- cremental value of added product (MPP multiplied by price) becomes less than the added cost of irrigation. Thus, Stage II, ranging from where APP is maximum to maximum TPP (MPP=0), is the economically rational range of irrigation assuming profit maximization. Beyond this point in Stage III, yields decrease with additional water (Heady, 1950). 4,000- - 4' A TPP g 3,000- B e 5' 2,000 J "-4 _ >' 1,000- g g g 5 E E, O0 s T10 1s 20 2s 30 1s0 APP ‘f5 100» """"""" ~. 1 E '0" ~\s‘ \ g ' I’ $‘\‘ O , MPP >- X‘ -so 0 s101s202ss0 SEASONAL IRRIGATION (m) Figure 1. Pronto water-yield response function (TPP), average physical product (APP), and marginal physical product (MPP). Table 1. Comparison of Pronto and McRan es- timated yields at selected irrigation levels, average rainfall. Average Rainfall‘ Seasonal % McRan lrrg. level McRan Pronto over Pronto lb/ac 0 2786 . 1974 41% 1 2795 2003 40% 2 2820 2045 38% 3 2861 2098 36% 4 2915 2163 35% 5 2981 2236 33% 6 3058 2319 32% 7 3143 2408 31% 8 3236 2504 29% 9 3335 2605 28% 1 0 3438 271 0 27% 11 3543 2817 26% 12 3650 2927 25% 13 3756 3037 24% 1 4 3859 31 46 23% 1 5 3960 3254 22% 16 4055 3359 21% 17 4143 3461 20% 18 4223 3557 19% 19 4293 3648 18% 20 4352 3731 17% 21 4397 3806 16% 22 4428 3872 14% 23 4443 3927 13% 24 4441 3970 12% 25 4418 4001 10% 26 4376 4018 9% 27 4310 4020 7% 28 4221 4006 5% 29 4106 3975 3% 30 3965 3925 1% lEstimated from equations 1 and 3. For Pronto, APP was maximum at approximately 19 inches and TPP was maximum at approximately 27 inches. Producers irrigating with less than 19 inches, in Stage I, would increase average productivity with in- creased water applications. If more than 27 inches of water is applied, yields would be expected to decrease as in Stage III; reducing crop income while unnecessari- ly increasing the cost of irrigation. Equation 1 can be simplified to a less complex func- tion, which may be more useful in practice, when rain- fall amounts are substituted for the precipitation variables. Thus, using rainfall quantities characteristic of the northern Texas High Plains as given above, the equation becomes: (2) Yp = 1,973.78 + 22.1944 I + 6.993612 - 0.1855 I3 where YP = in-shell yield of Pronto (lb/ ac) and I = seasonal irrigation (in). The influence of rainfall on yield is now included in the intercept term. Water-yield Response Function, McRan Cultivar Irrigation and rainfall also explained much of the yield variation for the McRan cultivar. The following fu ction explained 83 percent of the variation (R =O.830) in yields: (3) YM = -1,954.91 + 9.28 12 - 0.26 13 - 0.02 (I*]un)2 [429.2] [3.7] 10.12] 10.007] (455) (2.50) (-2.09) (-3.10) +1,231.57 IAS - 73.18 (IAS)2 [204.9] 117.9] $00 (40% R2 = 0.830 F = 44.94 n=48 where YM = in-shell yield of McRan (lb/ ac) and other variables are the same as above for equation 1. In the case of McRan, Stage II (Figure 2), begins with about 18 inches seasonal irrigation; only an inch less than Pronto. However, the end of Stage II where TPP is maximum is significantly lower at 23.5 inches com- pared with about 27 inches for Pronto. Estimated yields of McRan were higher than Pronto for equal irrigation 4,000 T; Q g 3,000 3 _ t_1_1 2,000» 5 3 3 >' U t! U “ )5 l f5 5 (l) ' (D 1D 1,o00- l O l l 1 l ‘I; l 0 s 10 1s 20 2s a0 150 I a l- ’ , ¢ ¢ ' ' ° " I §_ g 100V x," ‘ __ ; \ a o.‘ 1 a - ~.1 :- 0 l I ‘~ g‘ '50‘, MPP >- -100- l . , . 4500 s 10 1s 20 25 30 SEASONAL IRRIGATION (In) Figure 2. McRan water-yield response function (TPP), average physical product (APP), and marginal physical product (MPP). quantities up to 3O inches seasonal irrigation. Thus, McRan was estimated to be superior to Pronto in irriga- tion water-use efficiency (yield per unit seasonal irriga- tion water) at irrigation levels up to 30 inches with average rainfall conditions. The effects of rainfall deficits are discussed later. Table 1 compares the es- timated yields derived from equations 1 for Pronto and 3 for McRan with equivalent irrigation levels. Peanut producers with limited seasonal irrigation water supplies, as is typical of many areas in the southern High Plains, need to consider the superior water-use efficiency of McRan if a market exists for this type peanut and production costs and cultivar prices are similar. Non-traditional production areas such as the northern Texas High Plains where water supplies are generally adequate may want to consider both cul- tivars for production. Equation 3 also can be simplified by substituting rainfall quantities (given above) for the precipitation variables to become: (4) YM = 2,785.78 + 9.144 12 - 0.2613 where YM = in shell yield of McRan (lb/ ac), I = seasonal irrigation (in), and rainfall impacts on yield are now included in the intercept term. Profit Maximizing Level of Irrigation for Pronto The quantity of seasonal irrigation water which max- imizes profits, holding all other inputs constant, can be determined by equating the first derivative with respect to I of either equation 1 or 2 to the ratio of the irrigation cost and the price of spanish peanuts. Solving for I, for example, using an irrigation cost including both pump- ing and irrigation labor costs of $3.80/in (Texas Agriculture Extension Service, 1989a) and a Spanish peanut support price of $02878 / lb (USDA, 1989a), the maximum profit level would be nearly 26 inches seasonal irrigation in addition to the preplant irrigation. The calculations follow: dYp 2 $3.80 (5)— = 055651 + 13.98721 + 22.1944 = dI Thus, 0.1502 12 + 4.0255 1 + 2.5875 = 0 $02878 Using the quadratic equationl to solve for I gives (ignore the negative root): 4.0255 ;\/(4.0255)2 - (4) (-0.1s02)(2.5875) I= 2(-O.1602) I= 25.8 inches Optimum irrigation levels vary with irrigation cost and peanut price. Table 2 gives optimum irrigation levels for various irrigation costs ranging from $2 to Table 2. Maximum profit levels of seasonal irrigation with varying peanut prices and irrigation costs, Pronto and McRan. Peanut Price ($/lb) Irrigation 0.10 0.15 0.20 0.25 0.30 0.35 cost (mm inches Pronto: $2 25.2 25.7 25.9 26.0 26.1 26.2 $3 24.5 25.2 25.6 25.8 25.9 26.0 $4 23.7 24.7 25.2 25.5 25.7 25.8 $5 22.9 24.2 24.8 25.2 25.4 25.6 $6 21.9 23.7 24.5 24.9 25.2 25.4 McRan: $2 22.3 22.7 22.9 23.0 23.1 23.2 $3 21.7 22.3 22.6 22.8 22.9 23.0 $4 21.0 21.9 22.3 22.6 22.7 22.8 $5 20.3 21.5 22.0 22.3 22.5 22.7 $6 19.5 21.0 21.7 22.1 22.3 22.5 $6/ in and peanut prices ranging from $0.10 to $0.35 / lb. The results indicated optimum irrigation levels were relatively insensitive to changes in peanut price or cost of irrigation although relatively larger changes in op- timum irrigation levels were indicated as irrigation costs varied at a low price of peanut than at a higher price. For example, at a peanut price of $0.30/ lb, op- timum irrigation levels varied less than 1 inch when comparing the low irrigation cost of $2 / in to a high cost of $6/ in. The range of irrigation levels increased to 1.4 inches at $0.20/lb and, even wider to 3.3 inches at $0.10/ lb. Profit Maximizing Level of Irrigation, McRan Cultivar In the case of McRan, the profit maximizing level of irrigation using the same procedure was determined to be 22.8 in, which is 3 in less than Pronto at 25.8 in, with the same irrigation cost and a support price of $0.3054/ lb (USDA, 1989b). Table 2 indicates a similar lack of sensitivity to changes in peanut prices and irriga- tion costs for the maximum profit levels of irrigation for McRan as that of Pronto. lThe quadratic formula is based on the equation form y= aX2 + bX +c and is solved for X by: -b i v19 -4ac 2a X= Yield Responses to Alternative Timings of Irrigations Alternative timings of irrigations were also evaluated with respect to yield response. Over the years of research, but not necessarily every year, irrigations were applied at time intervals following planting of 21 days, 42 days, 56 days, 63 days, 70 days, 77 days, 84 days, 98 days, and 112 days. Day 42 represents the initial bloom stage of physiological development. This stage of development was presumed to be a critical water requirement period (Newman, 1979). Thus, all treatments were irrigated at day 42. Table 3a indicates the seasonal irrigation treatments, days-after-planting of each application, and net water applied by furrow irrigation after adjusting for runoff. Irrigation applications of Pronto peanut were statisti- cally significant at the 1 1 percent level or higher for days 21, 70, 77, 84, 98, and 112. The following functional relationship explained 88 percent of the yield variation: (5) YP = 190.82 + 109.18 D21R + 75.53 D7OR + 208.34 D77R + 95.92 D84R [220.8] (0.86) . [313] (3.49) [46.8] (1.61) [72.6] (2.87) [36.2] (2.65) + £47.09 D98R + 509.01 (D112R + HARVR) - 60.50 (D112R + HARVR) [29.6] (4.97) [261.6] (1.95) [35.9] (-1.68) R2 = 0.877 F = 40.787 where Yp = in-shell yield of Pronto (lb/ ac), D21R = irrigation quantity applied at 21 days plus accumulated rainfall 21 days after planting (in), D7OR = irrigation quantity applied at 70 days plus accumulated rainfall 64 to 70 days after planting (in), D77R = irrigation quantity applied at 77 days plus accumulated rainfall 71 to 77 days after planting (in), D84R = irrigation quantity applied at 84 days plus accumulated rainfall 78 to 84 days after planting (in), D98 = irrigation quantity applied at 98 days plus accumulated rainfall 85 to 98 days after planting (in), Standard errors of the regression coefficients are in brackets and T-values are in parentheses. The first ir- rigation after planting (day 21) and five of the seven mid- to late-season irrigations (days 70, 77, 84, 98 and 112) were significant in explaining yield variations. In- significant application times were days 56, and 63. Note that these results do not mitigate the impor- tance of irrigating at bloom (42 days) “if soil moisture and plant conditions warrant. The obvious absence of day 42 irrigation as a significant application time in equation 5 above is explained by the commonality of this irrigation in all treatments and years (Table 3a). High levels of irrigation around day 112 (in early September) combined with high rainfall to harvest in early October can reduce yields as is indicated by the negative quadratic relationship of these two additive variables. Negative impacts of this relationship would be expected to be lessened on highly permeable sandy soils. and (D112R + I-IARVR) = irrigation quantity applied at 112 days plus accumulated rainfall 99 to 112 days after planting and to harvest (about 30 days later) (in). llrrigation amounts are net furrow applications adjusted for runoff. Applications occurred within 2 to 3 days of that indicated depending on rainfall events. zExcludes equivalent multiple treatment application amounts in any one year, except where different amounts were applied w within the year in which case all treatments within the year were averaged. Table 3a. Seasonal irrigation treatments by year, timing of irrigations, and net amount of application. Applications - Days after Planting (Net applied)‘ Irrigation Treatment Year 21 42 56 63 70 77 84 _ 98 1 12 Total ‘vé/ finches) P + 2 1983 i 4.0 4.0 8.0 P + 3 1983 4.0 4.0 4.0 12.0 P + 4 1983 _ 4.0 4.0 4.0 4.0 16.0 P + 5 1983 4.0 4.0 4.0 4.0 4.0 20.0 1984 3.5 4.0 3.6 3.9 3.9 18.9 1985 1.9 3J3 3.7 4.5 4.2 17.6 1985 1.9 3.3 3.7 4.4 5.1 18.4 1986 4.0 2.7 3.1 3.8 3.0 22.5 1986 4.0 2.7 3.1 3.3 3.3 22.3 P + 6 1984 3.5 4 0 3.6 3.9 3.3 3.7 22.0 1985 1.9 3.3 3.7 3.7 4.3 3.4 20.3 1986 4.0 2.7 3.1 2.8 4.2 3.4 26.1 P + 7 1984 3.5 4.0 3.6 3.5 3.1 3.3 3.4 24.4 1984 3.5 4.0 3.6 3.5 3.1 3.3 3.7 24.7 1985 1.9 3.3 3.7 3.7 4.7 3.4 5.1 25.8 1986 4.0 2.7 3.1 2.9 3.2 ' 3.2 4.0 29.0 Averag - 3.13 3.50 3.60 3.28 3.71 3.99 3.5 4.1 3.7 20.5 of years T. In the case 0f McRan, the following relationship, which explained nearly 85 percent of the yield varia- tion, was developed: (6) YM = -931.61 + 172.91 D2lR + 167.10 D70R + 495.11 D77R 1343.61 120.71 161.01 158.41 (2.71) (8.35) (2.74) (3.49) + 253.58 D84R + 246.21 D98R - 3.25 (D84RxD98R)2 - 20.41 (HARVR)2 172.91 170.61 11.051 16.931 (3.4s) (3.49) (3.09) (2.95) R2 = 0.346 F =31.399 where YM = in-shell yield of McRan (lb/ ac), D2lR = irrigation quantity applied at 21 days plus accumulated rainfall to 21 days after planting (in), D70R = irrigation quantity applied at 63 days plus accumulated rainfall 64 to 7O days after planting (in), D77R = irrigation quantity applied at 77 days plus accumulated rainfall 71 to 77 days after planting (in), D84R = irrigation quantity applied at 84 days plus accumulated rainfall 78 to 84 days after planting (in), D98R = irrigation quantity applied at 98 days plus accumulated rainfall 85 to 98 days after planting (in), and HARVR = rainfall from 112 days after planting to harvest (about 30 days) (in). Significant irrigation applications included days 21, 70, 77, 84, and 98. All coefficients were significant at the 10 percent level of probability. Again, these results do not reduce the importance of a bloom irrigation at day 42 if conditions dictate. Insignificant applications were days 56, 63, and 112. Similarly, a reduction in McRan yield, as with Pron- to, would be expected to occur if rainfall is high during September and early October. The significance of the first seasonal irrigation at day 21 is again emphasized. Limitations The results of this relatively short 4-year investiga- tion were limited by the quantity and distribution of rainfall, by the limited number and levels of alternative irrigations, by the timing of rainfall events relative to irrigation applications, and, in certain cases, to a limited number of observations such as with D63 and D112. Although, on average, rainfall was near normal (90 percent), monthly and seasonal amounts were poorly distributed. In 1983 and 1984, the driest growing seasons, seasonal rainfall was 38 percent and 60 percent of the 26-year average rainfall, respectively, while 1985 and 1986 were characterized by one-month extremely wet periods resulting, respectively, in 118 percent and 133 percent of seasonal average rainfall. With respect to monthly distributions, both Iune and Iuly were below average for the study period with 63 percent and 52 percent of average, respectively. August rainfall was 110 percent and September, 139 percent of average for the 4 years. Furthermore, D21 yield response was fully evaluated in all years for only one irrigation treatment, preplant + 5 additional irrigations (P+5). In other years and irriga- tion treatments, the D21 irrigation was either included or excluded. However, low P+5 Pronto yield in 1983 when Iune rainfall was below normal resulted in a low seasonal water-use efficiency (including seasonal rain- fall) of 8O lb/ in compared with significantly higher efficiencies when the months of June also were extreme- ly dry in 1984 and 1986, and when Iune was wet in 1985. Water-use efficiencies for all treatments ranged from 106 to 118 lb/ in during these years; further indicating the importance of the D21 application. This early season irrigation was also observed to advance blooming date somewhat and may have advanced maturity, par- ticularly when June rainfall was low. Quality Considerations of Irrigation Treatments The preceding analysis of maximum profit levels of irrigation and the yield responses to irrigation amounts and timings of application did not consider potential quality or grade impacts of alternative irrigation levels on each of the two cultivars. Some selected and extraor- dinary climatic events during the 4-year period also may have affected the grade levels in the short growing season. For example, a record month-early frost oc- curred on Sept. 21, 1983, defoliating much of the leaf area prior to harvest. Yields of plant samples defoliated by frost in the highest irrigation treatment (P+5) were graded and a 4 to 5 percent decrease occurred in the percent sound mature kernels (SMK) and sound splits (SS) compared with selected undefoliated plants (data not shown). Another exceptional climatic event, un- characteristic of the northern Texas High Plains, oc- curred in 1985 when harvest was delayed by more than 8 in of rainfall in September and early October (Table 3b). Grades (%SMK + SS) of McRan were lower for all irrigation treatments than Pronto, indicating some field losses during harvest of mature peanut that would have increased the overall grade (data not shown). Regarding irrigation effects on grades (%SMK + SS), no significant impacts of irrigation treatments over the study period were found for Pronto (Table 4). However, in the case of McRan, the lowest irrigation treatment (P+2) graded significantly lower than P+4, P+6, and P+7 treatments. Also, McRan grades averaged significantly lower than Pronto over all irrigation treatments. Profitability of Pronto versus McRan Peanut Production The previous analysis of optimum irrigation levels with varying irrigation costs and peanut prices is useful in determining maximum profit application levels. No impacts on profits were evaluated with respect to cul- tivar grade differentials, however, and no estimate of about 70 percent SMK + SS and 4 percent OK. 1989 CCC profits per acre was made. A reassessment of the op- support prices based on these grades were $646.10/ ton “i . timal irrigation level was required due to the impacts for Pronto and $644.63/ ton for McRan (USDA, 1989a on price of the grades and grade differentials by cul- and b). The optimum irrigation levels (using an irriga- tivar. tion fuel and labor cost of $3.80/ in and the respective The average grade for 198336 of an 1,5,5, P+6I and peanut prices) were 25.9 in for Pronto and 23.0_in. for P+7 treatments for Pronto was about 73 percent SMK McRan. Yield estimates from Table 1 with these irriga- h . M R tion levels (rounded to the nearest inch) were 4,018 +58 and 4 percent 0t er kernels (0K) C an graded lb/ ac for Pronto and 4,443 lb/ ac for McRan. Enterprise Q, Table 3b. Monthly rainfall, net seasonal irrigation applied, total water, and treatment average yields by year and irrigation treatment. Rainfall Received Net Seasonal Total Irrigation Irrigation Seasonal Yieldz Treatment Year June July Aug. Sept. Applied‘ Water Pronto McRan (inches) -—— lb/ac _ P + 2 1983 1.60 1.30 0.15 0.20 8.00 11.25 797 232 P + 3 1983 1.60 1.30 . 0.15 0.20 12.00 15.25 951 600 P + 4 1983 1.60 1.30 0.15 0.20 16.00 19.25 2,042 1,668 P + 5 1983 1.60 1.30 0.15 0.20 20.00 23.25 1,854 1,067 1984 0.95 1.70 1.90 0.60 18.90 24.05 2,849 2,999 1985 2.90 0.35 0.75 6.14 _ 17.60 27.74 2,950 2,761 1985 2.90 0.35 0.75 6.14 18.40 28.54 3,283 3,034 1986 1.15 0.95 7.32 1.95 22.50 33.87 3,629 3,238 1986 1.15 0.95 7.32 1.95 22.30 33.67 3,579 3,463 P + 6 1984 0.95 1.70 1.90 0.60 22.00 27.15 2,988 3,233 193s 2.90 0.35 0.75 3.14 20.30 30.44 2,930 2,303 *4‘ 1986 1.15 0.95 7.32 1.95 26.10 37.47 3,296 3,575 P + 7 1984 0.95 1.70 1.90 0.60 24.40 29.55 2,990 3,259 1984 0.95 1.70 1.90 0.60 24.70 29.85 3,220 3,516 1985 2.90 0.35 0.75 6.14 25.80 35.94 3,650 2,375 1986 1.15 4 0.95 7.32 1.95 29.00 40.37 3,871 3,440 lRefer to Table 3a for irrigation amounts and timing of applications. zTreatment average of three replications. Table 4. Treatment means of peanut grades by cultivar. Pronto McRan lrrigationl %SMK + %ss"’ % OK %SMK + %ss’ %OK P + 2 73 a 4 63 b 7 P + 3 70 a 4 65 ab 7 P + 4 71 a 5 70 a 7 P + 5 73 a 4 68.5 ab 4 P + 6 72 a 4 70.5 a 3.5 P + 7 73 a 4 70.5 a 3.5 Cultig/ar Avg. 72 a 4.2 67.9 b 5.3 w lRefer to Table 3a for irrigation amounts and timings of applications. zMeans followed by the same letter in each column are not significantly different at the 5 percent level by Duncan's multiple range test. gt 3Means followed by the same letter are not significantly different at the 5 percent level by Duncan's multiple range test in this row. budgets are given in Table 5 for each type of peanut using a furrow application efficiency of 65 percent for these two levels of irrigation on a sandy loam soil (Musick et al., 1987). The preplant irrigation quantity used was a net 6 in application. (Sprinkler situations might require a higher cost per unit water applied but could reduce total water applied due to the ability to control both application amounts and depth of applica- tion, particularly in the amount and depth of preirriga- tion requirements.) The budgets were based on typical peanut cultural practices in the Texas I-Iigh Plains area and surface (furrow) irrigation. Production costs were estimated to be $483 / ac and $477/ ac including harvesting, hauling, and drying expenses for Pronto and McRan, respective- ly. The higher estimated yield for McRan resulted in higher gross income and higher returns to management and risk of $821 / ac compared with $673 / ac for Pronto using 1989 USDA support prices. Considering all costs except a charge for manage- ment, the breakeven price was $31 1 / ton for Pronto and $277/ ton for McRan. Thus, nonquota market prices would need to be substantially higher than the 1989 CCC loan rate of $149.75 / ton for nonquota production to be profitable in the absence of established quotas and production history. Assessment of Production and Profit Risks The previous discussion pointed out the potential of yield reductions associated with late-season irrigations and excessive rainfall in September on moderately per- meable soils. Using uation 5 with respect to late season irrigation and or rainfall to harvest, Pronto Table 5. Estimated profits of peanut production for the northern Texas High Plains by cultivar, furrow irrigated. ltem Pronto McRan $/ac Yield, lb/ac 4,018 4,443 Income $1,298.02 $1,435.15 Expenses: Herbicide 8.00 8.00 Nitrogen fertilizer, 40#/ac 4.40 4.40 Phosphorous fert., 80#/ac 16.80 16.80 Apply fert. 4.20 4.20 Seed + inoculant 45.25 45.25 Insecticide + appli., one 5.00 5.00 Fungicide + appli., three 30.00 30.00 Hoeing 11.00 11.00 Tractor fuel, lube 12.87 12.87 Tractor labor 15.51 15.51 lrrig. fuel, and labor1 187.08 169.54 Interest, 11% 16.31 15.83 Digging 10.00 10.00 Harvest and haul, $33lton 66.30 73.31 Drying, $25lton 50.23 55.54 Total variable costs 482.95 477.25 Returns over variable costs: 815.07 957.90 Fixed Costs: Machinery 40.11 40.11 Irrigation facilities 61.77 57.14 Land 40.00 40.00 Returns to mgm’t and risk: 673.19 820.65 Breakeven price/ton $311 .02 $276.61 llrrigation includes 6 in net applied for preirrigation. Source: Texas Agricultural Extension Service, 1989a. yields would begin declining with a total of 4.72 in or more rainfall after rnid-August based on a 3.7 in irriga- tion in early September (D112). The 26-year rainfall history at the North Plains Research Field, Etter, Texas, indicates this quantity was exceeded by rainfall 5 times or 19 percent of the time. In the case of McRan, equation 6 indicates rainfall during the month prior to harvest would reduce yields by 20 lb/ ac multiplied by the square of the amount received. The highest frequency of rainfall over the past 26 years was only about 0.5 in, reducing yields 5 lb/ ac; but on average, 1.6 in was received for a 51 lb/ ac reduction. Severe shortfalls in seasonal rainfall are expected to reduce yields. In the Texas High Plains, the highest frequency of rainfall quantities are less than the average monthly rainfall. The monthly modal rainfall or highest frequency was approximately 40 percent of the average for the months of June, July, and August and slightly less, 30 percent, for September. Continually dry seasons such as this are rare, though, occurring only 1 time during the past 26 years. If these conditions persisted, yields would be reduced nearly 200 lb/ ac for each cultivar. Profits from McRan would be reduced by $57/ ac and Pronto by $59 / ac. More common occurren- ces are dry monthly periods, such as July or August, in which approximately 20 percent of the time 40 percent or less of the monthly percent average rainfall was received over the past 26 years. Figures 3 and 4 depict the yield impacts of a July deficit. Pronto yields, Figure 3, were reduced 95 lb/ ac but McRan yields, Figure 4, 4°00 - a l- I YIELD (lbs/ac) 1on0 ‘ ‘ 70 77 B4 98 112 HARVEST IRRIGATIONS: DAYS AFTER PLANTING Figure 3. Pronto yields with average and 40 percent of average July rainfall. 1O were reduced 183 lb/ ac with 40 percent of average July rainfall. In this case, Pronto profits would be reduced $28/ ac and McRan, $54 / ac. 4000 ‘ AVERAGE JULY RAINFALL l \ 40% OF AVG. JLlLY RAINFALL 3000 YIELD (lbs/ac) 2000 1000 50° l . ' i l . 1 70 77 B4 90 HARVEST IRRIGATIONS: DAYS AFTER PLANTING Figure 4. McRan yields with average and 40 percent of average July rainfall. Literature Cited An, H.N. 1978. Light intensity effects on metabolism, growth, and yield components of peanuts. Diss. Abstr. Intl. 39z3083-B. Bausch, W.C., E.A. Hiller, and J.L. Tackett. 1971. Peanut response to water stress at various growth stages under sprinkler and furrow irrigation. SWR71-206, ASAE Southwest Region Meeting, Tulsa, Ok. Heady, Earl O. 1952. Economics of agricultural produc- tion and resource use. Prentice-Hall, Inc., Englewood Cliffs, New Jersey. Hiler, E.A., J.L. Tackett, and R.N. Clark. 1970. Peanut Response to different times and amounts of irriga- tion. 1970 Consolidated Peanut Progress Report, Texas Agri. Exp. Sta., College Station, Tx. Mantell, A., and E. Goldin. 1964. The influence of irriga- tion frequency and intensity on the yield and quality of peanuts (Arachis hypogaea). Israel J. Agr. Res. 14:203-210. Musick, J.T., F.B. Pringle and J.D. Walker. 1988. Sprinkler and furrow irrigation trends - Texas High Plains. Applied Engineering in Agriculture 4(1):46- 52. \ U U imttxkteilxivk‘..-ha.au~.~.s v _.._..».a. '91; “um Kkmiakril» deli-m National Weather Service. 1989. Unpubliishedidaitafi Amarillo Daily News, Amarillo,Texas. Newman 1.8., and M.L. Roberson. 1976. Supplemental irrigation of peanuts in northcentral Texas. 1976 Annual Research Progress Report, Texas Agr. Exp. Sta., College Station, TX. Newman, ].S. 1979. Sprinkler irrigation management for peanut production. Presented to Irrigation Management Work Group, 1979 Annual Con- ference, Texas Agr. Exp. Sta., College Station, TX. Reddi, G.I-I.S., and M.N. Reddy. 1977. Efficient use of irrigation water for wheat and ground nut. Mysore I. Agr. Sci. 11:22-27. SAS. 1985. SAS/ STAT Guide for Personal Computers. SAS Institute Inc., Cary, N.C. —S;tansell, JTR, and 1.1a. Pallas, Ir. 1985. Yield and quality response of Florunner peanut to applied drought at several growth stages. Peanut Sci. 12:64-70. Texas Agricultural Extension Service. 1989a. Texas crop enterprise budgets, Texas Panhandle district. B-1241(CO1), College Station, Tx. Texas Agricultural Extension Service. 1989b. Texas crop enterprise budgets, Texas South Plains district. B-1241(C02), College Station, Tx. USDA, ASCS. 1989a. Spanish peanut loan schedule - 1989 crop. Form 1014-5, Washington, D.C. USDA, ASCS. 19891b. Valencia peanut loan schedule - 1989 crop. Form 1014-2, Washington, D.C. 11 Mention of a trademark or a proprietary product does not constitute a guarantee or a warranty of the product by The Texas Agricultural Experiment Station and does not imply its approval to the exclusion of other products that also may be suitable. All programs and information of The Texas Agricultural Experiment Station are available to everyone without regard to race, color, religion, sex, age, handicap, or national origin. i.2M-lO-9O