Maximum barley production under varying soil moisture regimes
Assessing the effect of moisture availability and supply on barley growth and yield.
IPNI-1985-USA-MT5
13 Jun 2001
Methodology
- Field plots were established on the property of the Southern Agricultural Research Center, near Huntley an don the Du Beau-Nessan Ranch, near Forsyth Montana. A single lateral sprinkler irrigation delivery line, or line-source system was used to establish four soil moisture regimes at each site ranging from adequate moisture, M1, to increasing drought M2 , M3 , M4. Stripped across each moisture regime were 7 N fertilizer levels (0, 40, 80, 120, 160, 200, and 240 lb N/a). Nitrogen was applied preplant as aqua ammonia (20-0-0) via a squeeze-pump and fertilizer tubes attached to a tool-bar. The fertilizer was positioned in a deep-band 6" below the soil surface. Phosphorus was applied as phosphoric acid at a rate of 20 lbs/a actual P. The P was split-applied, 50% with the seed (seed-placed) and 50% in a deep-band with the N. Potassium was broadcast applied as KCl (0-0-60) at a rate of 40 lbs K/a. Barley was seeded in 12" rows at a rate of 86 lb/a. All plots were 6 rows wide and all treatment combinations were replicated 4 times in a RCBD.
Early season moisture conditions in the soil profile were extremely low due to extreme drought in the months prior to seeding and due to the fact that both sites were located on small grain recrop sites. While the extreme drought at both locations allowed for development of a wide range of soil moisture conditions during the growing season it caused problems related to crop emergence and stand establishment. Irrigation was applied across the entire study area on May 10 at Huntley (1.0") and May 22 at Forsyth (approximately 1.1"). Prior to this irrigation only 50% of the stand had emerged at either location. Water was applied as soon as it became available in the canal and irrigation ditch systems at each location.
Growing season precipitation amounts were extremely low at both locations, except during the week prior to harvest. Between August 1 and the date of harvest 2.1" and 2.4" of precipitation were recorded at Huntley and Forsyth. This rainfall had a negligible effect on yield as the crop was near maturity at both locations. At Huntley five irrigation events totaling 11.4", 7.7" 4.1" and 1.0" were applied to the M1, M2, M3, and M4 moisture regimes. At Forsyth four irrigation events totaling 11.0", 7.7", 3.8" and 0.9" were applied to the M1, M2, M3, and M4 moisture regimes.