The effectiveness of varying rates and timing of applied primary plant nutrients as a completely soluble N-P-K fertilizer through a drip/trickle low volume irrigation system was studied during 1991 on eggplant (Solanum melongena cv. Harris Special Hibush). Before the drip irrigation tubing and black plastic mulch were laid on a coastal plain sandy loam soil, plots were treated with 0, 22, 45, and 67 kg ha-1 of nitrogen (N), phosphate (P2O5) and potash (K20). The higher rates of preplant fertilization did have a significant beneficial effect on total seasonal yields of quality eggplants. The preplant treatments also had an influence on mid and late season production. As the frequency of drip/trickle applied primary plant nutrients increased up to 6 seasonal applications, the total quality fruit production substantially increased. Frequency of applications also had an influence on seasonal yields. Applying increased rates of the primary plant nutrients at a low seasonal frequency of 3 applications had little influence on increasing total quality yields of eggplants. Individual quality fruit was significantly heavier from plants which received 5 to 6 applications of the soluble N-P-K fertilizer than from plants which received no fertilizer through the drip/trickle irrigation system for the season.
James W. Paterson
Abbreviations: FLOOD. flood irrigations; RLD, root length density; TPAN, trickle irrigations scheduled based on Class A pan evaporation; TTEN, trickle irrigations scheduled based on tensiometer readings. 1 Associate Professor. The technical
Root distribution of trickle–and flood-irrigated 4-year-old `Ray Red' grapefruit (Citrus paradisi Macf.) trees on sour orange (C. aurantium L.) rootstock was studied utilizing a trench method. Irrigation treatments were: flooding at 50% soil water depletion, trickle irrigation (2 drippers per tree) at 0.5 Class A Pan evaporation or at 0.02 MPa soil tension. Two trees from each treatment were studied. Five 2.5 m deep trenches positioned perpendicular or parallel to the tree row at 0.6, 2.1, or 4.3 m from the tree trunks were dug per tree. After washing off a 0.5 cm thick layer of soil from the trench wall, 0.5 cm long root sections were marked on a transparent plastic film attached to the wall. Many roots of trickle-irrigated trees grew past the trickle wetted zone and extended beyond 2.1 but not 4.3 m of the trunk. However, the roots of flood-irrigated trees were present at all distances from the trunk. From 26 to 51% of the roots of trickle–irrigated trees were found 90-230 cm deep, despite the clayey texture of the top 1 m of soil which was underlaid by a sandy clay loam. The root systems-of flood-irrigated trees were shallower and in most cases confined to the top 90 cm soil layer.
Gail R. Nonnecke and Henry G. Taber
The purpose of this project was to investigate the use of evapotranspiration (ET) as a guideline for trickle irrigation timing in field-grown day-neutral `Tristar' strawberry. Proper management of trickle irrigation would allow optimum yields and quality with minimum water inputs. A randomized complete block field design with four replications was used at the ISU Horticulture Station in central Iowa. Irrigation treatments were based on % of ET and number of applications per week. The four treatments included: 30, 60, and 90 % of ET applied once per week (1X) and 30% of ET applied 3 times per week (3X). Total yield data (kg of fruit per season) indicated the 30% of ET (3X) treated plants yielded 15% more fruit than the 30% of ET (1X) plants. Berry number was 14% greater from plants receiving the 30% of ET (3X) treatment than from those receiving the 30% of ET (1X) treatment. Average berry weights for the entire growing season were similar among all treatments.
Thomas L. Thompson and Thomas A. Doerge
Two field experiments were conducted with subsurface trickle-irrigated romaine lettuce (Lactuca sativa L. cv. Parris Island Cos) during the 1990–92 winter growing seasons in southern Arizona. The objectives were to determine 1) yield and quality response to varying combinations of soil water tension (SWT) and N fertilizer, 2) seasonal patterns of N uptake, and 3) unutilized fertilizer N. During 1990–91, N rates were 35, 120, and 205 kg·ha–1. During 1991–92, the experiment was factorial with N levels from 50 to 300 kg·ha–1 and target SWT levels of 7.0 and 4.0 kPa. Unutilized fertilizer N was the difference between fertilized and nonfertilized plots in total N inputs not harvested in the crop. When excessive irrigation was not applied (SWT between 6.5 and 7.4 kPa), 95% of the maximum crop yield and yield quality (head length and fresh mass) response occurred at N rates of 156 to 193 kg·ha–1, with unutilized fertilizer N <60 kg·ha–1. Excessive irrigation (4.6 kPa) resulted in lower yields and yield quality and higher unutilized fertilizer N. Romaine accumulated >74% of its total N uptake in the 38 days before harvest. Unutilized fertilizer N increased sharply when adequate N and water rates were exceeded. These results suggest that a target SWT of no wetter than 6.5 kPa is appropriate for subsurface trickle-irrigated romaine lettuce.
James M. Dangler and Salvadore J. Locascio
Tomatoes (Lycopersicon esculentum Mill.) were grown on polyethylene-mulched beds of an Arredondo fine sand during two seasons to evaluate the effects of trickle-applied N and/or K, percentages of trickle-applied N and K (50%, 75%, and 100%), and schedules of N and K application on fruit yield, and leaf and shoot N and K concentrations. The daily irrigation requirement, calculated at 47% of the water evaporated from a U.S. Weather Service Class A pan (Epan), was met by the application of 4.6 mm to 7.2 mm water/day. Fertilizer was injected weekly in a variable (2% to 12.5% of the total amount weekly) or constant (8.3% of the total amount weekly) schedule during the first 12 weeks of each season. Trickle-applied nutrients and trickle-applied percentage of nutrients interacted in their effects on early, midseason, and total marketable fruit yields. When N + K and N were trickle-applied, the mean early total marketable fruit yield decreased linearly from 25.3 t·ha-1 to 16.3 t·ha-1 as the trickle-applied percentage of nutrients increased from 50% to 100%; but when K was trickle-applied (100% preplant-applied N), yields were not affected by the trickle-applied percentage (mean 26.3 t·ha-1). The weekly schedule of N and K injection had no effect on fruit yield or other characteristics. Higher leaf N and K concentrations early in the season were obtained when the respective nutrient was 50% to 100% preplant-applied than when the respective nutrient was 75% to 100% trickle-applied; but late in the season, higher concentrations were obtained when the respective nutrient was trickle-applied. Higher yields, however, were associated with higher early season leaf N concentrations rather than with higher late-season leaf N or K concentrations.
R.E. Zartman, L. Rosado-Carpio, and R.H. Ramsey
A 2-year study on the influence of trickle irrigation on the yield response of potato (Solanum tuberosum L. cv. Norgold Russet `M') was conducted at Lubbock, Texas. The objective was to evaluate the effects of trickle emitter placement on yield of #1, #2, marketable, cull, small, and total tubers. Trickle emitter lines were positioned 1) on the soil surface, 2) with the tuber pieces (4-inch depth), and 3) at S-inch depth. Irrigation was applied daily to replenish the water lost the previous day based on pan evaporation and crop coefficients. Marketable tuber yield was ≈ 8.9 to 11 tons/acre for all irrigation treatments. In both years, the proportion of misshapen potatoes (culls) was significantly greater for the S-inch depth irrigation treatment than for the surface or 4-inch depth treatments (2.9 vs. 0.71 and 0.67 tons/acre and 3.3 vs. 0.89 and 1.16 tons/acre, respectively). The misshapen tubers were directly influenced by trickle emitter placement and indirectly influenced by temperature differences within the tuber zone.
Thomas L. Thompson and Thomas A. Doerge
Three field experiments using subsurface trickle irrigation with various rates of target soil water tension (SWT) and N rates were conducted in southern Arizona during 1990–93. The experiments were conducted with collard (Brassica oleracea L. Acephela Group cv. Vates), mustard [Brassica juncea (L.) Czerniak cv. Southern Giant], and spinach (Spinacea oleracea L. cv. Indian Summer). The interactive effects of water and N treatments on crop yield, N uptake, and unutilized fertilizer N were studied. In general, excessive irrigation (SWT <5.6 kPa) resulted in lower yield and N uptake and higher unutilized fertilizer N. Optimum SWTs were 9 kPa for collard, 8 kPa for spinach, and 6 to 10 kPa for mustard.
James M. Dangler and Salvadore J. Locascio
Tomatoes (Lycopersicon esculentum Mill.) were grown on polyethylene-mulched beds of an Arrendondo fine sand during two seasons to evaluate the effects of trickle irrigation-applied N and/or K, percentages of trickle-applied nutrient(s) (50%, 75%, and 100%), and schedules of nutrient application (variable, 2% to 12.5% of total amount weekly, or constant, 8.3% of the total amount weekly) on the occurrence of fruit external and internal blotchy ripening and fruit mineral nutrient concentration. Trickle-applied fertilizer was injected into the irrigation water weekly during the first 12 weeks of each season. External and internal blotchy ripening were less severe with trickle-applied N supplied as N + K or N than with preplant-applied N. Trickle-applied N + K or N resulted in higher fruit concentrations of N, P, K, Ca, and Mg than with all preplant-applied N. Internal fruit quality improved slightly as the trickle-applied percentage of N and/or K increased from 50% to 100%, but significant differences in exterior quality were not obtained. Internal fruit quality was higher early in the season than late in the season during both years, but this response was not associated with fruit elemental concentration. The weekly schedule of nutrient injection had no significant effect on fruit quality or fruit elemental concentration. Highest yields of high-quality fruit were obtained with 50% trickle-applied N + K.
Brent Rowell and Mar Lar Soe
.L. Charlesworth, P.B. Cook, F.J. Thorburn, P.J. 2003 Analysis of soil wetting and solute transport in subsurface trickle irrigation Irr. Sci. 22 146 156 Das, B. Hazarika, P. Saikia, G. Kalita, H. Goswami, D.C. Das, H.B. Dube, S.N. Dutta, R.K. 2007 Removal of iron