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Recropping Spring Barley after Biosolids Fertilization

Gary Wegner
with: Dan Sullivan and Andy Bary, WSU Puyallup; Tim Pelton, City of Spokane

Objective

Compare yields and postharvest soil nitrate for the second crop after a single biosolids application.

Location: Reardan, WA
Previous crop: Barley, 1991; fallow, 1992; winter wheat, 1993
Soil: Kuhl silt loam
Annual precipitation: 14 inches

Treatments

(applied June, 1992 in summer fallow)

Check (No fertilizer)
Aqua ammonia, 60 lb N/ac
Biosolids, 3 dry ton/ac
Biosolids, 4.5 dry ton/ac
Biosolids, 6 dry ton/ac

Comments

No additional fertilizer was applied to any of the treatments for the 1994 crop. Following the 1993 harvest, the field was disked in the fall, and cultivated two times in the spring before planting. Spring barley (Baroness) was seeded 26 April 94 at 50 lb seed per acre with a 10 inch row spacing. Soil moisture was good at planting, and an excellent stand emerged. Aerial photos in early June clearly showed superior crop response (darker green color) on biosolids-treated plots. Low soil moisture and high temperatures severely stressed the crop starting in mid-June. Grain yields were measured with a weigh wagon on 15 Aug 94. A swath 37 by 970 ft (0.82 acres) was harvested from each plot. Average yield on the rest of the field (excluding the on-farm test) was 29 bushels per acre. Soil cores for nitrate analysis were collected in one foot depth increments using a Kauffman hydraulic soil auger on 31 Aug 94. Two soil samples per plot containing 9 soil cores (1 foot depth) and three cores (2, 3, and 4 foot depths) were collected.

Data

Grain Yield, bu/ac (15 Aug 94)

Treatment Rep 1 Rep 2 Rep 3 Rep 4 Average

Check 25.8 24.7 21.7 23.1 23.8a

Aqua ammonia 25.7 26.2 24.6 21.6 24.5ab

Biosolids 3T 26.5 30.1 31.1 27.9 28.9c

Biosolids 4.5 T 26.7 28.2 27.2 26.0 27.0bc

Biosolids 6 T 25.4 30.7 27.4 31.6 28.8c

LSD (5%) 3.1

CV 8%

Postharvest soil profile nitrate, lb N/ac/4 ft depth* (31 Aug 94)

Treatment Rep 1 Rep 2 Rep 3 Rep 4 Average

Check 23 32 35 25 29a

Aqua ammonia 47 104 32 52 59a

Biosolids 3T 54 90 84 53 70a

Biosolids 4.5 T 67 54 116 87 81a

Biosolids 6 T 112 132 235 72 138b

LSD (5%) 54.2

CV 47%

Conclusion

Biosolids application for the 1993 crop increased 1994 barley yields. The yield increase (about 4 bushels per acre) was small, due to soil moisture and heat stress conditions during grain fill. All biosolids rates performed similarly; yields were equal for application rates of 3.0, 4.5, and 6.0 dry tons per acre. Postharvest soil nitrate test results had high variability within a treatment. The additional soil nitrate found with biosolids application was equal to about 15 lb N per dry ton applied. We plan to plant spring grain again in 1995 to determine the residual value of the 1992 biosolids application.

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Hans Kok, WSU/UI Extension Conservation Tillage Specialist, UI Ag Science 231, PO Box 442339, Moscow, ID 83844 USA Redesigned by Leila Styer, CAHE Computer Resource Unit; Maintained by Debbie Marsh, Dept. of Crop & Soil Sciences, WSU