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Rita L. Hummel and Peter R. Bristow

In Spring 1996, `Meeker' red raspberry root cuttings were planted into a sandy loam soil in 30 cm tall x 27 cm diameter black plastic containers. During Mar. 1997, a second bottomless container was placed over the overwintering canes of half of the plants. The second container was filled with the same sandy loam soil to simulate ridging of the plants. All plants were grown using standard cultural practices on an outdoor, gravel nursery bed. Freeze tolerance of potted whole plants and excised root sections was measured at 5 °C intervals between -5 and -20 °C in a series of laboratory freeze tests conducted during Jan. 1998. Electrolyte leakage data were used to calculate the index of injury for excised roots while whole-plant response to freezing was determined by measuring the subsequent growth of floricane lateral shoots and of primocanes. After 1 month in the greenhouse, results indicated the dry weight of primocanes harvested from plants that were exposed to -20 °C was 56% of the nonfrozen control primocane dry weight. Primocane dry weight from plants exposed to -5, -10 and -15 °C was not different from the controls. Similar results were obtained for the percent of floricanes that were alive and for the dry weight of laterals produced by these floricanes after 3 months in the greenhouse. The whole-plant freeze test results indicated plants at the lowest temperature, -20 °C, were injured but not killed. Root index of injury of single potted plants averaged 5%, 15%, 29%, and 58% at -5, -10, -15, and -20 °C, respectively.

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Charlotte Mundy, Nancy G. Creamer, L. George Wilson, Carl R. Crozier and Ronald D. Morse

Conservation tillage using residue from a cover crop grown before potato (Solanum tuberosum L.) production has been infrequently and inconclusively studied. The objectives of this study were to 1) conduct a field study to evaluate soil physical properties, and potato growth and yield, in conventional-tillage (CT), no-tillage (NT), and subsurface-tillage (SST) systems and 2) conduct a greenhouse study to evaluate the effect of soil bulk density (ρb) on potato growth and yield. Potatoes (`Atlantic') were planted into residue of sorghum-sudangrass [Sorghum bicolor (L.) Moench × S. sudanense (Piper) Staph] at two sites in eastern North Carolina—Plymouth into Portsmouth fine sandy loam and Lewiston into Norfolk sandy loam. Potatoes in the NT and SST system emerged more slowly than potatoesplanted conventionally. There were no differences in plant population or size by 8 weeks after planting at Plymouth, but plant population and size were less in NT and SST systems at Lewiston. Reducing tillage also affected soil compaction, increased soil moisture early in the season at both sites, and increased ρb at Lewiston. Yield of U.S. No. 1 potatoes planted in NT and SST systems were comparable to potatoes planted in a CT system at Plymouth, but were less than potatoes planted in a CT system at Lewiston. There were no differences in yield between potatoes planted with NT and SST. In the greenhouse study, ρb did not affect leaf area or tuber yield or tuber grade. Specific sites and soils may allow for comparable potato production with no or SST, but further research, conducted on different soil types would promote further understanding of the impacts of reducing tillage in potato production.

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R.G. Linderman and E.A. Davis

Formation and function of arbuscular mycorrhizae (AM) are affected by levels of fertility in soil or fertilizers applied to soilless container mixes. For AM fungi, phosphorus (P) is the main element influencing colonization of host plant roots. The question addressed in this study was whether inorganic or organic fertilizers were more compatible with the formation and function of AM. Several controlled-release inorganic (CRI) fertilizers were compared with several organic (OR) fertilizers at different rates (½× to 4× the recommended rate) to determine (1) threshold levels of tolerance by the AM fungus Glomus intraradices in relation to root colonization, and (2) growth responses of `Guardsman' bunching onion (Allium cepa) and `Orange Cupido' miniature rose (Rosa spp.) plants grown in a soilless potting mix or sandy loam soil. AM colonization in soil was greatly decreased or totally inhibited by CRI fertilizers with high P content at the 2× rate or greater, whereas colonization was decreased but never eliminated by low-P OR fertilizers at the 3× rate or greater. Shoot growth of onions was similar with or without AM inoculation when fertilized with CRI, but in general was only enhanced by OR fertilizers if inoculated with AM fungi, compared to the noninoculated controls. Shoot and root growth of onions were significantly increased by AM inoculation when OR fertilizers were used at the 1× rate. In contrast, root growth was not increased by the combination of CRI fertilizers and AM fungal inoculation. Inoculation of miniature roses grown in sandy loam amended with 25% peat and perlite and fertilized with all the CRI or OR fertilizers resulted in high AM colonization, but without much AM-induced growth increase except where OR fertilizers or CRI fertilizers with low P were used. In a soilless potting mix, growth of miniature roses was less with OR fertilizers at the rates used than CRI fertilizers, but mycorrhiza formation was greater in the former unless P was low in the latter. These results indicate that release of nutrients from organic fertilizers, as a result of microbial activity, favors AM establishment and function more than most inorganic fertilizers unless P levels of the latter are low.

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Panayiotis A. Nektarios, Georgios Tsoggarakis, Aimilia-Eleni Nikolopoulou and Dimitrios Gourlias

Two field studies (winter and summer) were performed to evaluate the effect of three different fertilizer programs and a urea formaldehyde resin foam (UFRF) soil amendment on sod establishment and anchorage. Fertilizer treatments involved were 1) a quick release (QR) granular fertilizer (12-12-17); 2) a slow release (SR) fertilizer (27-5-7); and 3) a foliar (FL) fertilizer (20-20-20). The application rate was 50, 30, 0.35 g·m-2 for QR, SR, and FL, respectively. The substrate consisted of sandy loam soil, and in half of the plots UFRF flakes were incorporated in the upper 100 mm at a rate of 20% v/v. The effects of the fertilizer and soil amendment on sod establishment were evaluated through measurements of the dry weight of clippings and roots and the visual quality of the turf. Sod anchorage was measured by determination of the vertical force required to detach a piece of sod. For each treatment the initial and final pH, EC, available P, exchangeable K, Ca, Mg, and Fe were also determined. It was found that FL reduced clipping yield but retained turf visual quality similar to the other fertilizer treatments except in winter, when it resulted in the worst quality ratings. However, FL fertilizer promoted root growth and provided high vertical detachment force values and therefore enhanced sod establishment. Slow release fertilizer resulted in moderate top growth and visual quality of the turf during winter, but delayed sod establishment. Quick release fertilizer increased top growth and improved turfgrass visual quality during the winter, but root growth and vertical detachment force were reduced, indicating poorer sod establishment. UFRF did not enhance sod establishment since there was a negative effect on root growth when temperatures were below 10 °C, without however affecting vertical detachment force. Differences in soil P, K, Ca, Mg and Fe between treatments were inconsistent between the two studies, except for final K concentration, which was higher for QR fertilization than SR and FL. Foliar fertilization can enhance sod establishment compared to QR and SR, by accelerating sod anchorage and root growth. QR can be used in late autumn to improve winter green up of the sod. UFRF does not improve or accelerate sod establishment and possesses a minimal capacity to improve soil properties of sandy loam soils.

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Carl J. Rosen and Cindy B.S. Tongn

Two on-farm field studies were conducted in 1996 and repeated in 1997 to determine the effects of soil amendments and scape (flower stalk) removal on yield, dry matter partitioning, and storage quality of hardneck garlic (Allium sativum L.). One study site was on a loamy sand soil with low organic matter and fertility and the other site was on a sandy loam soil with high organic matter and fertility. Soil amendment treatments tested at both sites were: 1) no amendment, 2) composted manure, and 3) inorganic fertilizer according to soil test recommendations. A fourth treatment, dried, composted turkey-manure-based fertilizer, was included at the low organic matter site. Scapes were removed at the curled stage from plants in half of the harvest rows. Scapes from the remainder of the harvest row plants were allowed to mature until harvest. In 1997, bulbs from each treatment were stored at 0 to 3 °C or 19 to 21 °C for 6 months. Soil amendment treatments had no effect on total garlic bulb yield, dry mass partitioning, or stored bulb weight loss at the sandy loam, high organic matter site. Manure compost, fertilizer, and composted turkey manure soil amendments reduced the yield of smaller bulbs compared with the control at the loamy sand, low organic matter site. The proportion of bulbs >5 cm was highest with the manure compost treatment. At the low organic matter site, scape removal resulted in a 15% increase in bulb yield and an increase in bulb size compared with leaving scapes on until harvest (P = 0.05). At the high organic matter site, scape removal increased bulb yield by 5% (P = 0.10). Scape removal increased dry matter partitioning to the bulbs, but had no effect on total (scape + shoot + bulb) aboveground dry matter production. The increase in bulb dry mass when scapes were removed was offset by an increase in scape dry mass when scapes were left on. Bulb weight loss in storage was less at 0 to 3 °C than 19 to 21 °C. Soil amendments only affected bulb storage quality at the loamy sand, low soil organic matter site. The effect of scape removal on bulb weight loss was nonsignificant at either location.

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Harlene Hatterman-Valenti* and Paul Hendrickson

Field trials were initiated near Carrington and Absaraka, N.D., on a Heimdal clay loam and a Spottswood sandy loam, respectively to evaluate onion grade and yield in response to planting configuration, spring cover crop, and reservoir tillage. Results from the Carrington and Absaraka locations during 2002 and 2003 showed that colossal-sized onion was the largest grading size obtained (Carrington, 2003) and that the greatest number of colossal onion were from the bed configuration that had a reservoir tillage treatment. The coarser soil texture at Absaraka allowed for spring and fall formed raised bed comparison (2003) in which the fall formed raised bed tended to have greater yields and more marketable onion. Planting configuration resulting in the greatest total yield varied among locations and years but generally increased with reservoir tillage. Soil moisture and temperature monitoring during the early growing season did not differ greatly. However, differences in soil water potentials at the 6“ depth were observed during the last part of the growing season. Cover crop results indicated that a row of canola planted between onion rows for wind erosion protection will reduce onion yields even when ample water is available through routine irrigation. Herbicides for broadleaf control were not applied until onion had two true-leaves due to label restrictions. This delay enabled the canola to grow beyond the recommended stage for broadleaf control and to quickly outgrow the herbicide injury.

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Gerry H. Neilsen, Denise Neilsen, Peter Parchomchuk and Eugene Hogue

Soil solution monitoring has been suggested as an appropriate procedure to optimize fertigation timing and application rate. Soil solution NO3-N concentrations were measured for two growing seasons on a sandy loam soil when 5, 20 or 30 g N per season per tree were fertigated daily to apples as calcium nitrate from mid May-mid July. Soil solution NO3-N concentrations at 30 cm depth changed rapidly in response to both the initiation and cessation of fertigation, with values ranging from 10-20 ppm, 60-100 ppm and 100-200 ppm for the low to high treatments respectively. The rapid response to NO,-fertilizers implied a potential to control closely the timing of N fertilizer applications. In another experiment, `Empire' apple trees were fertigated 5 times/week from May 31 to August 9 with 30 g N/tree applied either as ammonium sulphate or as calcium nitrate. With calcium nitrate as the N source, NO3-N rapidly increased when fertigation was initiated and fell when fertigation ended. In contrast, with ammonium sulphate, NO3-N was low for about 30 days after initiation of fertigation, then increased to 100 ppm and remained elevated for 40-50 days after fertigation ended. The potential control of N nutrition appeared to be less exact when fertigating NH4-N.

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Ronald W. Garton

Processing tomatoes were planted on a sandy loam soil on raised beds which were prepared in a conventional method with a power bedder (PB), or with conservation tillage (CT). The CT treatments were prepared by using Glyphosate herbicide to burn-off a fall-seeded rye cover crop at either 10cm, 15cm or 30cm height. The center of the bed was tilled with a modified conservation tillage coulter caddy, prior to planting the tomatoes, to loosen the soil but leave the rye residue on the surface. Crop residue cover on the soil surface after planting the tomatoes increased from 9% in the PB treatment, to 63% with CT at 30cm. Increasing crop residue cover resulted in cooler soil temperatures during the day and warmer soil temperatures at night. Transplant survival and early growth was comparable between the tillage systems. Tomato yield was approximately 10% higher in the PB treatment than in the CT treatments. In the conservation tillage treatments, the tomato plants had lower total nitrogen concentrations in the petioles. Nitrogen immobilization by microbes in the decaying cover crop residue may have contributed to the lower petiole N concentrations, and the yield reduction.

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Bharat P. Singh and Wayne F. Whitehead

In literature, amaranth is described as a stress tolerant crop. However, most of the investigations have been concerned with the production of grain crop. The soil moisture regime which promotes maximum vegetative growth is yet to be established. During 1993, the vegetative growth response of amaranth to different soil moisture levels was determined in a greenhouse study. Amaranth cultivar Hin Choy was grown in Dothan sandy loam soil at four soil moisture levels of 6.0, 9.0, 12.0 and 14.0% (w/w) in a randomized complete block experiment with ten replications. Plant height, leaf number, leaf area, leaf fresh and dry weight, stem fresh and dry weight, root fresh and dry weight, leaf-stem ratio, and stem fresh and dry weight were recorded. All parameters gained significantly with each increment in the soil moisture level up to 12%. There was no difference in plant response between 12% and 14% soil moisture. The study indicated that for optimum vegetative growth, amaranth requires a moisture stress free soil environment.

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Mouna Benmbarek, Y. Desiardins and R.R. Simard

Landfiling and incineration constitute the most commonly used methods of biosolid disposal. To minimize the environmental risk, their chemical and biological characteristics have been the subject of several investigations.

The present research was undertaken to evaluate the agronomic value of municipal solid wastes (MSW) and composted de-inked sludge (CDS) in a field experiment for sod production. Four variables in a split factorial design, were investigated at two sod farms: compost (MSW and CDS), soil (sandy loam and clay loam), application method (surface applied 6cm and incorporated 20cm), and the application rate (50-100 and 150t/ha). Controls consisted of unfertilized and unamended but fertilized plots. Both experimental sites were seeded with kentucky bluegrass.

Preliminary data indicate that the two biosolids promoted the sod growth at the rates applied. However, a better plot cover was observed if composts were rototilled at a depth of 6cm as compared to the conventional treated plots. Measurements of root and foliar weights revealed that the turf growth was enhanced with increasing rates, which is probably caused by additional soil macronutrients showed by the analysis. Seed germination and seedling emergence were not delayed as indicated by the observed increase in the water retention capacity of the soil especially at higher compost rates.