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Fluid Journal : Fluid Journal 1996-1998
3 Fluid Journal Summer 1997 emergence on zero-till was generally higher than under conventional-till. For canola, crop emergence and yield on both systems were generally similar. The higher wheat yields on conventional-till soils were due to early stool development on warmer soils. On both tillage systems and for both crops there was a good response to N fertilizer and evidence of a moderate response to P, K, and S applications---even though crop emergence was significantly reduced at high fertilizer rates. Crop emergence Clay loam soil. In the relatively hot and dry 1995 season, high rates of N reduced crop emergence. But in 1996, under the influence of cool wet weather, application of N had no significant effect on wheat emergence but reduced canola emergence. In both years, wheat emergence was better on conventional- than on zero-till, while canola emergence was similar in both systems. Rainfall - inches 1995 1996 3.2 2.8 2.4 2.0 1.6 1.2 0.8 May June July August September Sandy loam soil. Crop emergence on sandy loam soil was lower than on clay loam soil because of the greater water- holding and nutrient-binding capacity of clay as compared to sand. It may be that sand permitted easier movement of nutrient from fertilizer band into the seed row where it can affect seed germination. As was observed for the clay soil, crop emergence in 1996 was better than in 1995. In both years, wheat emergence on conventional-till was better than on zero-till, while canola emergence under both systems was similar. In both years, at the highest combined rates of fertilizers (N, P2O5, K2O, and SO4), crop emergence declined. Decline was greatest for canola. In general, soil moisture at seeding and during germination in 1996 was good. Soils were relatively cool and there was a high plant emergence count. Furthermore, the presence of adequate soil moisture appeared to have modified the salt effect on germinating seeds caused by the presence of high rates of fertilizer---particularly N. This was not the case in 1995 when the seed bed was relatively dry, particularly on the sandy loam soil, and when the salt effect on the germinating seed would be great. Furthermore, some plants may have died on emergence as a result of high temperatures. There was some evidence that P enhanced emergence, particularly on clay soil. This was not the case for canola. Conditions/methodology Rainfall. The 1996 growing season was cooler and wetter than 1995, but temperatures increased rapidly as the season advanced. Although 1996 precipitation was below the long-term mean (Figure 3), it was well distributed and better than in 1995. Totals of accumulated precipitation for the '95 and '96 growing seasons were 66 and 78 percent of the long-term average, respectively. Plots. A four-replicate randomized complete block experiment was conducted on a Souris fine sandy loam and a Newdale clay loam in the Black Soil Zone (Orthic Chernozemic soils) of the Canadian prairie. Fugure 2. Monthly summary of rainfall, May 1 to September 30, 1996, Bailey and Grant, 1996. Table 1. Profile of soils and available nutrients for spring of 1995 and 1996, Bailey and Grant. Depth Clay loam Sandy loam in. 1995 1996 1995 1996 -----lbs/A----- pH (ppm) 0-6 7.8 7.8 7.5 7.5 NO3-N 0-10 33.6 28.0 22.4 31.4 P 0-6 16.8 21.3 25.8 19.0 K 0-6 VH VH 156.8 106.4 SO4-S 0-10 VH VH 28.0 40.3 VH = Very High
Fluid Journal 1993-1995
Fluid Journal 1999-2001