Yield Response of Corn to a Subirrigation/Drainage Management System in Northern Ohio

On most soils, even in the humid Midwest, lack of sufficient moisture at critical times often limits crop yields. Subirrigation/drainage (SID) is a relatively new concept in water management, where drain lines are used both to add or remove water from the soil to maintain a constant water table. By the use of a SID system, significant increases in soybean (Glycine max L. Merr.) yields have been obtained. The.potential also exists for SID to increase corn (Zea mays L.) yields. The objective of this research was to determine whether corn yields could be increased and stabilized at high yield levels by the use of SID systems. Two 3‐yr SID studies on corn were conducted, one at Wooster in northeastern Ohio, 1990 to 1992, on Ravenna silt loam (fine‐loamy, mixed, mesic Aeric Fragiaqualfs), and one in northwestern Ohio, 1992 to 1994, near Hoytville on a Hoytville silty clay loam (fine, illitic, mesic Mollic Ochraqualfs). Results of this research indicated significant increases in corn yields can be obtained in dry years but in favorable moisture years little yield increase was observed. These data indicate that corn yields can be stabilized at high levels (180 to 200 bu/acre) by the use of SID, resulting in higher long term average yields. Research Question Variation in rainfall results in erratic corn yields from year to year on many Midwestern soils. The objective of this research was to assess the feasibility of obtaining consistent high corn yields by the use of a subirrigation/drainage system to maintain a constant water table throughout the growing season. Literature Summary A relatively new concept in the irrigation of field crops is the use of subirrigation/drainage systems. Drain lines are used in reverse during dry periods to subirrigate. Since the same system is used both for drainage, to remove excess moisture, and for subirrigation during periods of moisture shortage, it provides a total water management system. Not all soils are suitable for subirrigation/drainage. The soils have to be fairly level and poorly drained (able to hold water). Also a source of water is essential. Prior research by the authors indicated that consistent 70 to 80 bu/acre soybean yields could be obtained by combining a high yield soybean production system with subirrigation/ drainage to maintain a constant water table throughout the growing season. In favorable moisture years, Midwest corn yields of 200 bu/acre, or higher, have been obtained by researchers and growers, but consistently high yields have not been possible. At the Ohio Agricultural Experiment Stations, located at Wooster and Hoytville, corn yields vary from 80 bu/acre in a dry year to 200 bu/acre in favorable moisture years. The objective of this research was to determine whether consistently high corn yields could be obtained by the use of a subirrigation/ drainage system. Study Description Subirrigation/drainage research facilities were established at the Ohio Agricultural Research and Development Centers at Wooster in 1984 and at the Northwest Branch at Hoytville in 1990. These systems consist of 4‐in. diameter corrugated plastic drain tubing installed at 36‐in. depth with 20 ft spacing between lines. The drain lines are connected to a main and an adjustable control stand near the outlet used to regulate the water table level in the field. At Wooster, the water table was maintained at an average depth of 16 in. (10 in. over the drain to 22 in. at the midpoint between the drains). At Hoytville, two water table depths were compared, 10 in. and 20 in. depth over the drain lines. At both sites, groundwater was supplied from a well. To maintain a constant water table in the soil, the water was continuously pumped into the control stand at a rate sufficient to balance crop use, seepage and evaporative losses. Drainage only was used as the control (check) treatment at both locations. Fertilizer was applied as needed to obtain and maintain high soil test levels for P and K and preplant and sidedress N applied to give a total of 300 lb N/acre. Four row plots with 30‐in. row spacing and 60 to 80 ft long were used with the row direction perpendicular to the direction of the drain lines. The center 2 rows were harvested for yield. Applied Question Can the use of a subirrigation/drainage system result in consistently high corn yields on Midwest soils adapted to subirrigation/drainage? Consistent corn yields, in the 180 to 200 bu/acre range, were obtained at Wooster (1990–1992) and Hoytville (1992–1994) with the use of a subirrigation/drainage system. In the driest year at Wooster, 1991, the drainage only plots produced 66 bu/acre compared with 198 bu/acre for the subirrigated plots. The driest year at the Hoytville site was 1993 where the drainage only plots yielded 135 bu/acre compared to 196 bu/acre for the 10 in. water table depth. Two out of the 3 yr at each location, where the moisture conditions were more favorable, resulting in 180 to 200 bu/acre in the drainage only plots, yields were not significantly increased by subirrigation. These data suggest that in more favorable moisture years, and under subirrigation/drainage, some factor other than water is limiting corn yields to the 190 to 200 bu/acre yield levels. However, because of the potential for large yield increases in dry years, and the ability to obtain consistent yields in the 180 to 200 bu/acre yield range every year, over a period of years, subirrigation/drainage should significantly increase average corn yields for growers who have land suitable for subirrigation and an available water supply.