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Controlled drainage‐subirrigation (CDS), conservation tillage, and corn (Zea mays L.) production practices were evaluated as methods of reducing NO−3 loss through tile drainage. Controlled drainage‐subirrigation was used to manage water from precipitation and subirrigation. Samples of tile drainage (5801) and surface runoff (3274) water were collected with autosamplers during each runoff event over a 3‐yr period. Annual tile drainage volumes were reduced 24% with CDS compared with the drainage (DR) treatments. Flow weighted mean NO−3 concentration of tile drainage water was reduced 25% from 10.6 mg N L−1 for the DR treatments to 7.9 mg N L−1 for the CDS treatments. The average annual NO−3 loss was reduced 43% from 25.8 kg N ha−1 for the DR treatment to 14.6 kg N ha−1 for the CDS treatments. Eighty‐eight to 95% of the NO−3 losses from all treatments occurred in the noncrop period (1 Nov.–31 Apr.). Conservation tillage in combination with CDS reduced annual NO−3 losses 49% (11.6 kg N ha−1) when compared with the conventional moldboard plow tillage and DR treatment. Annual NO−3 loss through surface runoff was increased to 1.9 kg N ha−1 with the CDS treatments compared with 1.4 kg N ha−1 with the DR treatment, this loss was minor compared with losses incurred through tile drainage. Controlled drainage‐subirrigation is a technological advancement in soil and water management as it enables farmers to minimize the effect of dry summers on crop growth and reduce NO−3 contamination of drainage water.

No‐tillage systems on fine‐textured soil are not well suited for corn (Zea mays L.) because of problems with excess water, lower temperatures, and residue management during the early stages of corn growth. This is a problem, as corn is commonly used in rotation with wheat (Triticum aestivum L.) and soybean [Glycine max (L.) Merr.]. Furthermore, when corn follows winter wheat there may be additional problems associated with residue management during the early stages of corn growth. Hence, the objectives of this study were to measure the effect of the red clover (Trifolium pratense L.) cover crop underseeded in wheat and no‐tillage on soil temperature, water content, corn emergence, surface residue, and yields in a wheat‐cornsoybean rotation in southwestern Ontario. Treatments included conventional vs. no‐tillage both with and without underseeded red clover in a wheat‐corn‐soybean rotation in a clay loam soil. A no‐tillage and red clover treatment that had the wheat straw baled was also included. No‐tillage (with and without red clover) increased soil water content by 2 to 5% and reduced soil temperatures by 1 to 2°C during early corn emergence. Soil drying occurred along the planting slot of the no‐tillage treatments, which enabled the soil seed furrow to open and the corn seedlings to become water stressed even though the notillage treatments were wetter in the spring. Corn emergence in the no‐tillage treatment without red clover was delayed by 3 to 4 d and the final plant stand was reduced by 24% compared with the conventional tillage treatment. The no‐tillage treatment without red clover had 13% lower corn grain yield than the conventional tillage treatment averaged over three years. However, when red clover was included with no‐tillage, corn emergence was increased and corn grain yields were not significantly different from conventional tillage in both 1994 and 1996. There was also 15% less dry weight of surface plant residue present in the no‐tillage treatments when red clover was included. Hence, red clover alleviated some of the problems of no‐tillage for corn production.

Conservation tillage has become an attractive form of agricultural management practices for corn and soybean production on heavy textured soil in southern Ontario because of the potential for improving soil quality. A controlled drainage system combined with conservation tillage practices has also been reported to improve water quality. In Southwestern Ontario, field scale on farm demonstration sites were established in a paired watershed (no-tillage vs. conventional tillage) on clay loam soil to study the effect of tillage system on soil structure and water quality. The sites included controlled drainage and free drainage systems to monitor their effect on nitrate loss in the tile drainage water. Soil structure, organic matter content and water storage in the soil profile were improved with no-tillage (NT) compared to conventional tillage (CT). No-tillage also increased earthworm populations. No-tillage was found to have higher tile drainage volume and nitrate loss which were attributed to an increase in soil macropores from earthworm activity. The controlled drainage system (CD) reduced nitrate loss in tile drainage water by 14% on CT site and 25.5% on NT site compared to the corresponding free drainage system (DR) from May, 1995 to April 30, 1997. No-tillage farming practices are definitely enhanced by using a controlled drainage system for preventing excessive nitrate leaching through tile drainage. Average soybean yields for CT site were about 12 to 14% greater than the NT site in 1995 and 1996. However, drainage systems had very little effect on soybean yields in 1995 and 1996 due to extremely dry growing seasons.

benefits of conservation tillage with the yield benefits of conventional moldboard plow tillage (e.g., Pierce et Despite extensive research, reduced corn (Zea mays L.) performance is still encountered using conservation tillage on fine-textured al., 1992) for cool humid climatic zones. Here, a narrow soils in cool humid temperate climates. These problems are intensified zone 10 to 20 cm wide by 10 to 30 cm deep is conventionwhen corn is planted into residue from a previous crop such as winter ally tilled in the crop row while the rest of the soil surface wheat (Triticum aestivum L.). The objective of this 4-yr study was is left in an untouched no-till state. This supposedly to determine the influence of fall zone tillage (ZT), no tillage (NT), encourages the more favorable soil temperature, moisand conventional moldboard plow tillage (CT) (fall plowing) on corn ture, aeration, density, and strength conditions associperformance and soil physical quality under a winter wheat-cornated with conventional tillage in the narrow seedbed soybean (Glycine max L. Merr.) rotation with and without red clover (Trifolium pratense L.) (RC) underseeded in the wheat phase of the zones, while retaining the increased erosion resistance, rotation. A randomized complete block design (3 ϫ 2 factorial, 4 organic matter protection and reduced energy inputs of replicates) was established on three adjacent fields in the fall of 1996 no tillage between the zones. Although there is much on a Brookston clay loam soil (fine loamy, mixed, mesic, Typic Argiainterest in the zone-till system, it has not yet been tested quoll) at Woodslee, ON Canada, and measurements were collected extensively in cool humid temperate climates, nor on during 1997 to 2000. Over both wet and dry growing seasons from the agriculturally important clay and clay loam soils of 1998-2000, zone tillage following underseeded RC produced average southern Ontario. In nearby Michigan, ZT on sandy corn grain yields (7.23 Mg ha Ϫ1) that were within 1% of those obtained using conventional tillage (7.33 Mg ha Ϫ1), and 36% higher than those loam soils did indeed improve potato (Solanum tuberoobtained using no tillage and RC (5.33 Mg ha Ϫ1). Zone tillage also sum L.) yields and soil physical conditions relative to improved soil quality as evidenced by generally lower soil strength conventional tillage in most years of a 4-yr study (Pierce than no tillage, and near-surface soil physical quality parameters that and Burpee, 1995); however, corn yields were not inwere equivalent to, or more favorable than, those of the other treatcreased by zone tillage in a similar 3-yr study, despite ments. It was concluded that corn production using zone tillage and substantially reduced soil strength (penetration resis-RC underseeding is a viable option in Brookston clay loam soil, as it retains much of the soil quality benefit of conventional tillage but tance) within the 0-to 30-cm depth range (Pierce et still achieves most of the yield benefit of conventional moldboard al., 1992). plow tillage.

Agronomic and economic assessments of response of processing tomato (Lycopersicon Esculentum Mill.) to nutrient application with drip fertigation are essential to optimize soil fertility management that maximizes farmers' profi tability in a sustainable manner. A fi eld study was conducted to evaluate the yield and economic responses of drip fertigated processing tomatoes to additions of fertilizer nitrogen (N) and phosphorus (P) from 2003 to 2005. Th e experiment was arranged in a factorial design with four levels of fertilizer N (0, 120, 240, and 360 kg N ha -1 ) and three levels of fertilizer P (0, 100, and 200 kg P 2 O 5 ha -1 ). Fertilizer N application aff ected biomass yield of stems and leaves, total and marketable fruit yields, N use effi ciency, and N agronomic effi ciency. However, neither P application nor the interaction between fertilizer N and P infl uenced these variables. Nitrogen use effi ciency and N agronomic effi ciency decreased with increases in fertilizer N rate, with N use effi ciency averaging 443 kg kg -1 and N agronomic effi ciency averaging 237 kg kg -1 . Both fruit yields and net economic returns responded quadratically to the fertilizer N rate, with a maximum marketable yield of 127 Mg ha -1 averaged across the 3 yr. Th e fertilizer N rates were 271 kg N ha -1 for the maximum marketable yield and 265 kg N ha -1 for the optimum economic yield. Th ese values are considerably greater than the current recommendation, due to the largely increased yield with drip fertigation. Fertilizer N should be applied at an increased rate for processing tomatoes with drip fertigation to maximize the economic return.

Atrazine (6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine) and metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] have been found with increasing occurrence in rivers and streams. Their continued use will require changes in agricultural practices. We compared water quality from four crop-tillage treatments: (i) conventional moldboard plow (MB), (ii) MB with ryegrass (Lolium multiflorum Lam.) intercrop (IC), (iii) soil saver (SS), and (iv) SS + IC; and two drainage control treatments, drained (D) and controlled drainage-subirrigation (CDS). Atrazine (1.1 kg a.i. ha-1), metribuzin [4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazine-5(4H)-one] (0.5 kg a.i. ha-1), and metolachlor (1.68 kg a.i. ha-1) were applied preemergence in a band over seeded corn (Zea mays L.) rows. Herbicide concentration and losses were monitored from 1992 to spring 1995. Annual herbicide losses ranged from < 0.3 to 2.7% of application. Crop-tillage treatment influenced herbicide loss in 1992 but not in 1993 or 1994, whereas CDS affected partitioning of losses in most years. In 1992, SS + IC reduced herbicide loss in tile drains and surface runoff by 46 to 49% compared with MB. The intercrop reduced surface runoff, which reduced herbicide transport. Controlled drainage-subirrigation increased herbicide loss in surface runoff but decreased loss through tile drainage so that total herbicide loss did not differ between drainage treatments. Desethyl atrazine [6-chloro-N-(1-methylethyl)-1,3,5-triazine-2,4-diamine] comprised 7 to 39% of the total triazine loss.