The residual soil NO 3 -N concentration is used in determining the N fertilizer recommendation for many crops in the arid UnitedStates. Accurate representation of the field levels of residual NO 3 -N is complicated by the fact that the NO 3 concentration in a soil sample can change significantly if the sample is not handled properly after collection. This will result in erroneous N fertilizer recommendations.Soil samples were retained in their field moist state after collection and subjected to various conditions that would be encountered under normal soil sample handling situations before they were dried and analyzed. Subsamples were removed periodically to determine the change in NO 3 -N as influenced by the various handling conditions. Samples with an original NO 3 -N concentration 169 of 26 ppm increased by 30.4, 12.8, 27.5 and 36.4 ppm when incubated (30 C), refrigerated, kept at room temperature or placed in a window where they were exposed to the sun 7 hours/day over a 7 day period, respectively. These changes would result in N fertilizer errors ranging from 52 to 147 kg N/ha (based on a 0-30 cm sample depth). During the first 48 hours after collection the same treatments resulted in changes in NO 3 -N concentration that would cause N fertilizer errors in the range of 24.3 to 57.3 kg N/ha. Seven different soils were used in these investigations and only one showed a significant change in NO 3 -N concentration upon freezing or air drying for 7 days. Although these changes were statistically significant they were so small that the error in the resultant N fertilizer recommendation would be meaningless.Based on the results obtained, soil samples should be dried immediately after collection. Since "immediate" drying is not always logistically possible, samples should be placed in a dryer within 12 hours after collection recognizing that changes in NO 3 -N will occur but the magnitudes of these changes will be relatively small when translated to N fertilizer recommendations.

Poor fruit germination and emergence of sugarbeet (Beta vulgaris L.) due to moisture and temperature stress can limit satisfactory stand establishment. Our objective was to evaluate laboratory procedures which measure germination and emergence potential under moisture and temperature stress and to use these tests for development of fruit treatments for improving field emergence under stress conditions.Germination tests were conducted on blotter paper using polyethylene glycol 600 osmotic solutions to induce moisture stress. Emergence through a 2.5 cm layer of greenhouse soil mix (Ascalon sandy loam and peat, 1:1 V/V) was used to evaluate the effect of fruit treatments on emergence under moisture and temperature stress. The soil mix, initially at —1/3 bar matric potential, dried to —10 to —5 bar matric potential during the course of the test. Emergence through a 3.3 can layer of packed silica sand (3.5% water — wt/wt) was used to evaluate treatments under temperature, moisture and impedance stress tests conducted at 9, 15, or 26 C. Field trials were used to confirm results of laboratory tests.Germination of sugarbeet fruit decreased with increas. ing osmotically simulated moisture stress from 0 to —7 bar water potential after which no germination occurred. Increasing the moisture stress from 0 to —4 bar potential decreased the rate of germination, but not the final germination percent, while both rate and final germination percent decreased sharply as moisture stress went from —4 to —8 bars. Removal of the pericarp decreased the water requirement for germination at a given rate by 2 bars, indicating that the pericarp is a major factor limiting germination and emergence under moisture and temperature stress.Treatment of the fruit with 1.0 N HCI for 2 hours significantly improved germination and emergence under moisture and temperature stress conditions in laboratory and field trials. Excessive acid treatment damaged the true seed. The acid treatment did not improve the emergence where impedance was the major stress or in the absence of moisture and temperature stress. Temperature affects not only the rate and extent of germination, but also the moisture requirement. The sugarbeet fruit germination at —5 bar matric potential and 26 C was equal to that at —1 bar and 9 C.The germination of untreated fruits of eight cultivars ranged from 26 to 72% at —1 bar matric potential and 9 C, and from 6 to 20% at —5 bar and 9 C. Acid treatment improved germination of all cultivars, but low germinating cultivars were improved the most.

The recovery of sucrose from sugarbeets (Beta vulgaris L) has decreased in recent years while root yield has increased. Our objective was to determine the effect of N application rate and topping method on root yield and on the factors affecting recovery of sucrose‐sucrose content, purity, and storage loss. The effect of five N fertility levels (0, 67, 134, 202, and 269 kg/ha) on sugarbeet root yield, quality (percent sucrose and percent purity) and crown tissue size was investigated from 1975‐1977 in 10 field experiments in Colorado, Kansas, and Nebraska. Crown tissue, the portion of the sugarbeet above the lowest leaf scar, increased from 10.64 to 16.03% of the total root weight as the N application rate increased from 0 to 260 kg/ha. Total root yield increased from 45.2 to 54.4 metric tons/ha over the same N range, but much of the yield increase was due to increase in crown size. Sucrose content and clarified juice purity (CJP) decreased 1.42 and 1.97% units, respectivdy, as the N application went from 0 to 269 kg/ha. The decrease in quality offset the increase in yield so that increasing rates of N had no significant effect upon yield of recoverable sucrose per ha. The extractable sucrose per metric ton of beets was reduced from 144.5 kg/ton for the 67 kg N/ha application to 128.6 kg/ton for the 269 kg N/ha application. Crown removal significantly reduced yield of recoverable sucrose per hectare but only increased extractable sucrose per ton from 136.7 to 140.0 kg/ton. Quality (sucrose and CJP) was improved both by proper topping and by N management, however, N management has a more dramatic effect upon quality. Total sucrose yield is reduced by topping, but not significantly affected by N application rate. Three N fertility levels (0, 134, and 269 kg/ha) and three topping methods (flailed, half‐topped, and topped) were evaluated for their effect on sucrose and quality changes in sugarbeet roots during storage in nine experiments. Failed beets had 27.4 and 25.5% less gross sucrose and recoverable sucrose losses than regular topped beets and 17.3 and 15.7% less gross suaose and recoverable sucrose lass than half‐topped beets. Method of topping had a significant effect upon sucrose losses in beets grown in all Iri levels. Nitrogen application rate had no significant effect upon gross sucrose or recoverable sucrose losses. Beet quality (extractable sucrose per metric ton) was higher in topped beets than flailed beets at harvest, but no difference existed between topping treatments after storage. Sucrose production per acre and beet quality was maximized with the low fertility, flailed treatments before and after storage.

No abstract

No abstract