Updated June 29, 2018:
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Conservation tillage and soil water management are key components for soybean production in smectitic Fargo clay soil. Installing subsurface drainage is common practice in water logged area which has potential to cause yield loss. Integration of subsurface drainage and reduced tillage (no-till or strip till) can improve soil health and remove excess water leading to increased soybean production. Extent of subsurface drainage benefit depends on its design, depth of tile and spacing in between drain. We are conducting an on-farm long-term experiment to determine the effects of (i) subsurface drainage and tillage interactions and (ii) subsurface drain depth and spacing combinations on soybean production. This experiment is located at Ron Holiday farm near Casselton, ND.
For the first objective, three tillage practices, (i) chisel (CH), (ii) strip-tillage (ST), and (iii) no-tillage, are compared for soybean production under only surface-drained condition (check), controlled drainage and conventional drained conditions. Soybean yield in 2017 growing season is presented in Figure 1. The highest soybean yield was observed with chisel plough under check (surface drainage) whereas, lowest yield was observed under convention drainage and strip tillage. The outcome indicate performance depends on the growing weather condition, 2017 was dry year with only 217 mm of rainfall which is very low when compared with 30-year average of 397 mm during same growing season.
For the second objective, combinations of three subsurface drain spacing, 30-, 40-, and 50-feet and two depths, 3 feet and 4 feet, are evaluated for soybean production (figure 2). During 2017, the highest soybean yield of 30.5 Bu/ac and the lowest yield of 23.2 Bu/ac were found under 30 feet tile spacing at 4 feet depth (30_4) and surface drained, respectively. In 2015, the highest yield of 56.85 Bu/ac was observed with 40 ft drain spacing at 3 feet depth and the lowest yield was recorded under 50 feet tile spacing at 4 feet depth (50.16 Bu/ac).