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Fall vs. Spring CRP Takeout - Summer Fallow - Fall Plant in Lincoln County

Develop BMP's for optimizing tillage methods and timing for returning CRP land back to a rotation of fall or spring takeout - summer fallow - winter wheat.

Location: Lincoln County, east of Lamona, WA.
Soil series: Renslow silt loam
Annual precipitation: 10 inches
Field history: Crested Wheatgrass for 8 years

1. Fall disc* - spring sweep* - fertilize - summer fallow - plant
2. Spring disc* - fertilize - summer fallow - plant
3. Spring flail - disc* - fertilize - summer fallow - plant
4. Spring burn - spring sweep* - fertilize - summer fallow - plant
5. Fall harrow - spring disc* - fertilize - summer fallow - plant

*plus a tine harrow

Comments

Initial residues taken on 30 September 1994 ranged from 4232 to 7495 lbs/ac with an average of 5658 lbs/ac. The plot size is 50' by 1250' with 4 replications. Soil samples taken on 19 April 1995 showed total N to be 123 lbs/ac, P at 15 ppm, K at 492 ppm, and S to 3' at 12 ppm. Fall harrow occurred on 5 October 1994 and the fall disc occurred on 2 November 1994. The spring flail occurred on 6 March 1995. Glyphosate was sprayed on 28March 1995 at a rate of 16 oz/ac. Primary spring tillage began on 19April 1995. The plot was fertilized on 10 June 1995 at a rate of 50-0-0-8. Spring soil moistures to 6' were taken on 3 April 1995. The plot was planted on 24 August 1995 with Eltan winter wheat at a rate of 55 lbs/ac. Residue cover was taken after planting using the line point method. Surface picture roughness measurements were taken using D.K. McCool's random roughness pictures.

Table 1. Results from fall vs. spring CRP take-out study in Lincoln Co, WA, 1995.

Treatments	Available Moisture Spring 1995 (inches/6')	Available Moisture Fall 1995 (inches/6')	Residue Cover (8/25/95) (%)	Plant Stand (plants/M2)
1. Fall disc	5.5b	5.2a	16.0a	97.1a
2. Spring disc	5.6b	5.3a	14.6ab	98.1a
3. Spring flail	6.0ab	5.4a	13.0b	99.8a
4. Spring burn	6.8a	4.9a	4.1c	98.5a
5. Fall harrow	5.7b	5.3a	13.5b	103.7a
LSD (10%)	0.9	0.6	2.1	12.0
CV (%)	12.0	9.3	13.4	9.6

Table 2. Results from fall vs. spring CRP take-out study in Lincoln Co, WA, 1995.

Treatments	Surface Roughness (Picture 7/20/95) (inches)	NRCS Picture Residue Cover (7/20/95) (%)	Surface Roughness (Picture 8/25/95) (inches)
1. Fall disc	0.75b	50.8a	0.69b
2. Spring disc	0.73b	48.5ab	0.73b
3. Spring flail	0.77b	40.4c	0.72b
4. Spring burn	0.85a	14.4d	0.82a
5. Fall harrow	0.77b	44.1bc	0.75b
LSD (10%)	0.04	5.5	0.06
CV (%)	4.3	10.9	6.9

Conclusion

Significant differences in soil moistures were shown between treatments with fall treatments retaining the least amount of moisture. The summer fallow period appears to be highly efficient, this is due to a late season rain that occurred right after planting. Residue cover showed significant differences between treatments with the spring burn retaining the lowest amount of residue and the highest surface roughness. Plant stands between treatments were not significantly different.

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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