Fertigation of Fluid Nitrogen and Phosphate Fertilizers for Pears in

Pacific Northwest

Xinhua Yin

Mid-Columbia Agricultural Research and Extension Center

Oregon State University

Current N and P Management System

80-100 lbs N/acre100-125 lbs P2O5/acre

Not close to roots

High application rate

Over- or under-application

Low application flexibility

Split N and P Fertigation

1. Closer to root system.

2. Lower dose - split application.

3. Avoid over- and under-application.

4. Higher application flexibility.

5. Increase growth and yield in the early years.

6. Save time - automatic delivery system.

Objectives

Compare fruit yields, quality, and storability under split fertigation of N and P or band application of N and P with broadcast application of dry N and P to the soil surface.

Compare the costs on installing and maintaining a N and P fertigation system with those on the surface broadcast of dry N and P system.

Treatments

1. Surface broadcast of N & P.

2. Band application of N & P.

3. Broadcast application of N & P to the soil surface plus soil disturbance by band application (no fertilizer).

4. Split fertigation of N & P (80% of N & P).

5. Split fertigation of N & P under micro sprinkler irrigation (80% of N & P).

Fertigation & Irrigation System

Soil total N, amino sugar N, NH4+, NO3

-, total P, available P, pH, and organic matter.

Leaf N, P, K, etc.

Tree vigor.

Fruit yield, size, firmness, color, and sugar.

Fruit storability.

Sampling and Measurement

Soil Nutrients after Pear Harvest

Trt Total N Amino sugar N

NH4-N NO3-N Total-P Available P

(%) (ppm) (ppm) (ppm) (ppm) (ppm)

1 0.208c 259.0 1.48 36.6 1310.5 30.3

2 0.261ab 344.4 1.98 59.2 1387.0 43.5

3 0.271a 233.1 1.53 67.6 1256.8 37.0

4 0.234bc 298.2 1.85 8.4 1195.3 36.0

5 0.295a 302.4 1.80 14.4 1255.8 36.8

Sig. * ns ns * ns ns

Leaf Nutrition after Pear Harvest

Trt N P K Ca Mg S B Zn Mn Cu

(%) (%) (%) (%) (%) (%) (ppm) (ppm) (ppm) (ppm)

1 1.90bc 0.101b 1.17 2.35 0.28 0.23c 88.9 169.4 67.3 6.3

2 1.99ab 0.106b 1.43 2.19 0.26 0.25ab 98.1 188.7 70.9 7.6

3 1.80c 0.104b 1.18 2.52 0.30 0.24bc 87.2 170.6 74.9 8.0

4 2.07a 0.118a 1.45 2.24 0.28 0.25a 104.5 180.6 66.5 7.7

5 1.99ab 0.127a 1.39 2.33 0.26 0.25ab 98.2 182.0 69.6 8.1

Sig. * * ns ns ns * ns ns ns ns

Fruit Yield

0

50

100

150

200

250

300

Surface broadcast Band application

Surface + disturbance Fertigation

Fertigation/Micro

Yie

ld (

lbs/

tree

)

Treatment

a a a a a

Fruit Quality

Trt Sugar Firmness Titratable acid

(obrix) (lbs) (meg/100 ml)

1 13.2a 14.2b 4.6b

2 13.4a 14.2b 5.1a

3 12.8ab 14.3b 4.4b

4 13.0ab 15.3a 4.7ab

5 12.3b 14.8ab 4.5b

Sig. * * *

Fruit Scald

Trt Excellent Very slightly Slightly Moderately Severely

% % % % %

1 25.0 40.0 15.0 15.0 5.0

2 40.0 42.5 17.5 2.5 0.0

3 25.0 27.5 22.5 15.0 10.0

4 37.5 42.5 10.0 10.0 0.0

5 35.0 42.5 12.5 7.5 2.5

Sig. * * * * *

Summary

• Split fertigation of N and P slightly increases pear yield and size compared with surface application of dry N and P Fertilizers.

• Split N and P fertigation or banding application significantly reduces fruit scald.

• Split fertigation of N and P reduces N and P fertilizer uses by 20%.

Acknowledgments

Fluid Fertilizer Foundation Hood River Grower and Shipper AssociationPotash and Phosphate Institute

Thanks!!!

Questions???