IRRIGATION AND NUTRIENT MANAGEMENT IN TREE FRUIT PRODUCTION SYSTEMS.

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1 IRRIGATION AND NUTRIENT MANAGEMENT IN TREE FRUIT PRODUCTION SYSTEMS Neilsen, D 1, Neilsen, G 1, Forge T 1 denise.neilsen@agr.gc.ca 1 Agriculture and Agri-Food Canada, Summerland, B.C. Canada KEYWORDS Irrigation and nutrient management are linked; micro-irrigation; irrigation scheduling; available soil moisture; automated irrigation systems; nutrient availability in the root zone; matching nutrient demand and supply. ABSTRACT In irrigated production systems water management often controls nutrient availability. For apple, the change to dwarfing rootstocks and increasing tree density has provided the opportunity to focus water and nutrient inputs into the root zone, but this means that management needs to be more precise. As rootstock vigor decreases, the volume of soil accessed by the roots decreases Retention of nutrients in the root zone for as long as possible improves the chance of root uptake, increasing nutrient use efficiency and reducing fertilizer costs. This can be achieved by conservative water management and by applying fertilizer at the right time, rate and placement to meet plant requirements. Water management options include micro-irrigation systems which are well-engineered to meet peak demand and correctly designed for the crop/soil combination; mulches to reduce soil evaporation and irrigation scheduling. The amount of water required, depends on the stage of crop development, the amount of evapo-transpiration or precipitation that has occurred since the last irrigation and soil type. The lower the frequency of irrigation (subdaily to several day intervals), the more important soil type becomes. Improving water management by scheduling irrigation to meet crop demand has the benefit of saving water (Figure 1) nutrients and potentially improving fruit quality. Figure 1. Water and nitrogen retention in the root zone is determined by irrigation scheduling and timing of N applications. Losses are higher when irrigation is not scheduled to meet plant demands.

2 The most effective way to schedule irrigation is through fully automated monitoring systems based on estimates of evapo-transpiration and soil moisture measurements, which can then be used to control the irrigation system. The most effective way to match nutrient requirements to plant demand is through fertigation (applying nutrients through the irrigation system), which works best with drip and small radius micro-sprinkler. Nitrogen (N) is particularly suited for this as it is very mobile in soil and water, but because of that it is also difficult to control. In this case it is best to apply small amounts frequently (e.g. daily) and match the timing of application to plant demand. For apple and other tree fruits, it has been shown that there is little uptake from the soil until bloom as N which has been stored over-winter in the tree is used for early spring growth. Applying N during fruit cell division (approximately 6 weeks after bloom) promotes fruit and canopy development. Later N applications may have detrimental effects on fruit quality. If low, tree N status may be improved by postharvest foliar urea applications just before leaf senescence. Boron (B) is another mobile nutrient, like N, which can be fertigated. Phosphorus (P) is particularly important for tree root growth and early establishment. It can be applied pre-plant as a granular fertilizer and fertigated early in the season. A single large application is more effective than multiple small ones and should not be mixed with other fertilizers. Potassium (K) can become depleted under drip irrigation and fertigation or if ammonium N sources are used in other systems, particularly in coarse-textured (sandy) soils. Fruit removal of K can be double that of N, and if leaf K approaches deficiency, K applications do not negatively affect fruit storage quality.

3 Irrigation and nutrient management in tree fruit production systems Denise Neilsen, Gerry Neilsen and Tom Forge Pacific Agri-Food Research Centre, Summerland, BC. Canada WSU Fruit School, Wenatchee WA. Nov. 17, 2015

4 Irrigation requirements adequate supply prevent stress maximize yield improve fruit quality M in 0-16in more challenging in high density plantings with restricted roots

5 Water Loss via Evapotranspiration (ET) Solar radiation Wind Evaporation from the leaf surface and soil surface Transpiration from leaf stomates Open water vapor lost Dry soil Water stress Low growth Closed CO 2 for growth assimilated

6 Plant water stress affects fruit size < 100% ET Irrigation 100% ET Irrigation Even with optimum irrigation plants can sometimes experience stress In well watered trees sap flow (transpiration)was reduced when daily ET >0.28 in/day or Max T >95C

7 Strategies for managing water well Applying water to meet plant requirements (irrigation scheduling) Conservative, well engineered systems Reducing soil water evaporation

8 Growing season ET (in/year) Peak ET (in/day) Peak flow requirement (US gpm/acre) Well designed irrigation systems meet daily peak ET and total needs Peak daily ET Summerland CS Weather station April-Oct Average = 0.27in Design flow rates for peak ET (BCMA Sprinkler and Trickle Irrigation Manuals) Micro-irrigation Sprinkler irrigation Peak ET (in/day) Growing season ET Summerland CS Weather station April-Oct The weather information is available from WSU Ag weather net:

9 Well-designed irrigation systems take into account soil water availability SATURATED SOIL drainage AVAILABLE WATER BOUND WATER Drying Important if soil is being used for water storage characteristic of sprinkler irrigation water is usually applied at intervals greater than 2-3 days For micro-irrigation, soil storage becomes less important if: water is applied at high frequency (<2 day intervals) in amounts to meet evaporative demand soil moisture is maintained at a high level

10 36 in Water what is really available Modified according to soil type, crop rooting depth, crop ability to extract water (allowable depletion) How frequently should it be replenished? - as often as possible Grape Apple Grape Apple Grape Apple 3.0in 1.2in 0.5in 4.6in 1.9in 0.73in 7.6in 3.0in 1.2in Sand Sandy loam Silt loam

11 Water applied (in) Improving water management with irrigation scheduling how long an irrigation system should run matches water supply to demand uses some measurement or estimate of demand (soil moisture, climate)

12 Soil Moisture Monitoring Electrical Resistance Block manual, semi-automated can be fully automated Capacitance probes (fully automated record) TDR manual can be automated Tensiometer manual can be automated Soil moisture range for micro-irrigation systems Soil Type Soil moisture tension low (wet) (cbars) high (dry) Sand Loamy sand Sandy loam loam 25 30

13 Crop coefficient (Kc) Estimating tree water use from potential evapotranspiration (ET 0 ) Actual water use (mm or in) = K x ET 0 (in) K is the crop coefficient and is related to canopy size K is the in water required per in of ET Apply 0.5 in/in ET 0 Apply 1.2 in/in ET Weeks after shoot leaf budburst

14 Automated sensor systems Example of a multi-sensor system, communicating to various devices. There are others on the market Schematic of a multi-sensor system, which controls the irrigation system S e n s o r s Electronic switch Pressure transducer Datalogger, computer Solenoid valve Irrigation controller Irrigator

15 Water (in) (Kc) Soil moisture (%) Targeting water in the root zone using automated sensing scheduling 30 Drippers 15 cm from emitter Microsprinklers 15 cm from emitter Weeks after budburst Addition Loss Rainfall Water use PET Microsprinkler Day of the year Low drainage & N loss Day of the year Water supply and demand can be matched very well with automated scheduling and microirrigation

16 Nutrient management in irrigated production In irrigated production systems water and nutrient management are closely linked and water management controls nutrient availability Compact root systems and microirrigation offer good opportunities for controlled application of nutrients Precision nutrition can reduce inputs and improve fruit quality M in 0-16in

17 Nitrate-N (ppm) Nitrate-N (ppm) Fertigation can control N in the root zone over the growing season Broadcast Irrigated weekly with sprinkler 10 day increased N availability Day of the year Soil N supply controlled with frequent small applications (N1) (N3) Day of the year Fertigated daily with drip

18 N (g/tree) When should N be applied in Tree stored N moves into spur, shoot leaves and fruit Bud break spring? 0 Fruit Apply fertilizer after bloom Petal Full fall bloom Day of the year Root uptake into shoot leaves and fruit End of cell division Shoots Spur leaves Before petal fall leaf growth (spur leaves) supported by remobilized N Root uptake occurs mainly after bloom to support shoot and fruit growth N inflow into fruit occurs mainly after cell division 1oz. = 28.4g

19 Percentage of total stored N (%) When should we apply Fall foliar urea? Leaf N content (g m -2 ) N from leaf N from spray In trees with low leaf N, fall urea applications may increase N storage for growth next year In high N trees foliar urea is not necessary Re-drawn from Cheng et al., 2002 J. Hort. Sci &Biotech 77

20 How much N? - removal in fruit and senescent leaves of apple trees oz/tree lb/ac* Golden Delicious/M.9 first year Gala/M.9 third year Elstar/M.9 fourth year Gala/M.9 sixth year assumes a tree density of 1350 trees/ac

21 N loss (lb/acre) Water loss (gal/tree) Water and N drainage reduced by irrigation scheduling in Gala/M b a Scheduled to meet ET Unscheduled (fixed rate) b a fertigation period b a May June July Aug. Sept. Oct-May May b a water losses high under unscheduled irrigation during periods of low ET water and N losses related during fertigation period irrigation scheduling keeps N in the root zone

22 Soil P (ppm) Soil P availability - Fertigated phosphorus in apple (drip irrigation) Single application Year 1 Year 2 Year 3 50 Single large fertigated application can keep P available 2-3 months Day of the year

23 Cumulative Yield (lb/tree) Fruit P (mg/100g F.W.) Phosphorus effects on fruit production - 5 apple cvs/m * Cumulative Yield ( ) -P +P Fruit P concentration ** ** ** Phosphorus additions are effective when targeted to the roots through fertigation (20g actual P/tree) as Ammonium Polyphosphate 21

24 Leaf K (% dw) Effect of fertigated K on leaf K concentration 2 Averaged for four apple cultivars (Gala, Fuji, Spartan, Fiesta) b b 1 a a b a a b a b 1.3% 0 Yr 1 Yr 2 Yr 3 Yr 4 Yr 5 0g K/acre/year 45lb K/acre/year

25 Effects of K fertilizer forms on leaf K concentration in Braeburn/M c ab ab a ab ab a a a 1.5 c 1.3% K Check KCl KMag K 2 SO 4 KTS Treatment applied at 90lb K/acre

26 Bitter pit incidence averaged over 3 years K applications in a low K orchard did not increase bitter pit Check KCl KMag K 2 SO 4 KTS Treatment

27 Assumes 1333 trees/acre Summary: slender spindle apple nutrition Nutrient Form Application duration Application rate (g/tree) N ; Can 17; Urea P (P-acid) Daily 6 weeks after bloom One day after bloom 60lb N/ac If using then 30 lb/ac 45lb P/ac 45lb P + 30lb N/ac K (KCl) K 2 SO 4 ; Kmag; KTS; Daily for 6 weeks starting 4 weeks after bloom 60lb K/ac KNO 3 B Solubor (20.3% B) Daily for 6 weeks starting 4 weeks after bloom 0.51lb B/ac

28 Thank you