Influence of long-term residue management on soil enzyme activities in relation to soil chemical properties of a wheat-fallow system

Summary Soil enzyme activities (acid and alkaline phosphatase, arylsulfatase, -glucosidase, urease and amidase) were determined (0- to 20-cm depth) after 55 years of crop-residue and N-fertilization treatment in a winter wheat (Triticum aestivum L.)-fallow system on semiarid soils of the Pacific Northwest. All residues were incorporated and the treatments were: straw (N₀), straw with fall burn (N₀FB), straw with spring burn (N₀SB), straw plus 45 kg N ha^–1 (N₄₅), straw plus 90 kg N ha^–1 (N₉₀), straw burned in spring plus 45 kg N ha^–1 (N₄₅SB), straw burned in spring plus 90 kg N ha^–1 (N₉₀SB), straw plus 2.24 T ha^–1 pea-vine residue and straw plus 22.4 T ha^–1 of straw-manure. Enzyme activities were significantly (P<0.001) affected by residue management. The highest activities were observed in the manure treated soil, ranging from 36% (acid phosphatase) to 190% increase in activity over the control (N₀). The lowest activities occurred in the N₀FB (acid phosphatase, arylsulfatase and -glucosidase) and N₉₀ treated soils (alkaline phosphatase, amidase and urease). Straw-burning had a significant effect only on acid phosphatase activity, which decreased in spring burn treated soil when inorganic N was applied. Urease and amidase activity decreased with long-term addition of inorganic N whereas the pea vine and the manure additions increased urease and amidase activity. There was a highly significant effect from the residue treatments on soil pH. Arylsulfatase, urease, amidase and alkaline phosphatase activities were positively correlated and acid phosphatase activity was negatively correlated with soil pH. Enzyme activities were strongly correlated with soil organic C and total N content. Except for acid phosphatase, there was no significant relationship between enzyme activity and grain yield.Journal Paper No. 8072 of the Agricultural Experimental Station, Oregon State University, Corvallis, OR 97331, USA     

Temporal variation of mercury in vegetation

Temporal changes in the Hg content of balsam fir needles (Abies balsamea) and white spruce needles (Picea glauca) were monitored at a control site over two growing seasons. Results indicated a significant increase in the Hg content of needles of both species over the course of a growing season and from one year to the next. The Hg content of new foliage more than doubled within each growing season, and was 5–10 ng g^?1 higher in the 1990 growing season than in the previous year. These results indicate that temporal variation is a potential source of error when mapping the spatial variation of Hg concentrations in vegetation. To minimize this source of error, field surveys should be completed as quickly as possible (i.e., within two or three weeks).     

Nutritionally relevant parameters in low-phytate barley (hordeumvulgare L.) grain mutants

Nutritionally relevant parameters in barley low-phytate mutant grains were analyzed in order to assess the potential value of these lines for future feeding trials. Phytate (myo-inositol 1,2,3,4,5,6-hexakisphosphate) levels in grains from A- and B-type low-phytate mutants corresponded to 25% and 66% of those of the parent line content, respectively. These relative decreases in phytate were accompanied by proportional increases of inorganic phosphate amounts. Apart from phytate, A-type grains also contained substantial quantities of myo-inositol 1,3,4,5-tetrakisphosphate. Phytate levels in straw and root material from mutants were similar to parent line controls, indicating that low-phytate mutations were grain specific. Analysis of K, Mg, Ca, and Zn revealed normal or slightly increased mineral cation levels in grains from all low-phytate lines, suggesting that mutationally impaired phytate accumulation did not affect mineral storage capacity. Other nutritionally important parameters such as starch and protein contents were similar to parent line controls. Finally, dynamic changes in the phosphorus composition during kernel development suggested that A-type mutations directly affected phytate synthesis, whereas B-type mutations seemed to act on regulation of synthesis.     

Rapid detection of propiconazole and tebuconazole in wood by solid phase desorption: ion mobility spectrometry

The durability of wood is improved by wood preservatives. Due to new environmental legislation, commonly used active ingredients such as chromium and arsenate are being replaced by alternative and more environmentally friendly preservatives. However, the alternative wood preservatives are more difficult to detect in the wood. Detection of the preservatives is necessary in order to monitor millwork production for qualitative assessment of the wood preservative uptake. The aim of this study is to examine the use of solid phase desorption-ion mobility spectrometry (SPD-IMS) can be used for rapid detection of the wood preservatives propiconazole and tebuconazole in Scots pine (Pinus sylvestris). The findings proved that SPD-IMS is capable of detecting and distinguishing wood preservatives directly from treated wood shavings. SPD-IMS requires no additional sample preparation or extraction of the wood sample. The findings show that SPD-IMS is a fast and easily applied method for direct detection of propiconazole and tebuconazole in small wood samples.     

Indole-3-butyric acid accelerates adventitious root formation and impedes shoot growth of Pinus elliottii var. elliottii?×?P. caribaea var. hondurensis cuttings

Many plantation tree species are cloned to achieve the growth, disease resistance and wood quality characteristics required for a successful economic venture. However, clonal propagation is limited by declines in adventitious root formation with increasing stock plant age. We examined the effects of immediate or delayed IBA application on adventitious root formation and subsequent root and shoot development of cuttings harvested from 8-year-old clonal hedge plants of Pinus elliottii var. elliottii × P. caribaea var. hondurensis. IBA applied at the time of setting accelerated root formation, elevating the percentage of cuttings with roots at 13 weeks post-setting from 45 to 78% and from 83 to 93% for a low- and a high-rooting clone, respectively. Final rooting percentages for the same treatments and clones (78 and 85%, and 88 and 100%, respectively, at 20 weeks post-setting) were not significantly affected by IBA application. IBA increased the root:shoot ratio of rooted cuttings by decreasing shoot weight compared with untreated cuttings, without affecting root weight, root length, root surface area or root volume. IBA was only effective when applied at the time of setting. A simple IBA treatment for cuttings from 8-year-old clonal hedges, by accelerating root production, has potential for reducing nursery costs and increasing the root system quality of containerised pine cuttings.     

The effect of autumn ridging and inter-row subsoiling on potato tuber yield and quality on a sandy soil in Denmark

Autumn ridging is a modified version of the ridge tillage system. Instead of setting up ridges during the growing season, they are established in autumn and left for the winter. Previous studies have documented positive effects of autumn ridging on potato yield and we hypothesized that subsoiling could enhance these effects. To determine the effect of autumn ridging and inter-row subsoiling on potato yield and quality a field experiment was conducted on sandy soil from 2001 to 2003. Autumn ridging resulted in an average total and marketable tuber yield of 25.6 and 9.2 t ha⁻¹, which was not significantly different from the average total and marketable yield of 25.6 and 8.9 t ha⁻¹ with ploughing. However, autumn ridging significantly reduced the incidence of black scurf from 2.5% to 2.2%. Inter-row subsoiling in the growing season significantly increased marketable potato tuber yield from 8.4 to 9.6 t ha⁻¹ and reduced the occurrence of malformed potatoes from 9.3% to 7.5%, irrespective of tillage treatment and irrigation level. There was no significant interaction between autumn ridging and subsoiling. The beneficial effect of subsoiling on marketable yield was driven by a 48.5% increase in the dry year of 2001. Subsoiling reduced the incidence of common scab from 7.8% to 6.9% when irrigation was reduced. It is concluded that at least three factors may modify the effects of subsoiling: Soil water status in the growing season, precipitation immediately before and after the subsoiling operation, and crop growth stage at the time of subsoiling.     

Survival of sea‐water‐adapted trout,Salmo trutta L. ranched in a Danish fjord

The effect of seawater adaptation on the survival of coastally released post‐smolt trout, Salmo trutta L., was investigated by release: (1) directly (with no adaptation); (2) after retention in net pens in the sea for 29–131 days (delayed release); (3) after feeding with a high‐salt diet (12–13.5% NaCl) for 4 weeks; and (4) after a combination of (2) and (3). In total, 17 640 trout (age = 1+, 1.5 and 2+ years; mean fork lengths = 18.2–25.6 cm) were released in 14 batches in the summer or autumn months of 1986–1989. All fish were of domesticated origin and Carlin tagged. Survival and instantaneous mortality rates (total and fishing mortality) were estimated from reported recaptures. Mortality rates were estimated for: (1) the post‐smolt period; (2) the period until the legal size of capture (40 cm) was attained; and (3) for larger sea‐trout. Release with a delay of 4 weeks gave an increased survival rate. A longer adaptation period did not increase survival. On average, survival was increased by 36%. Survival was not increased by high‐salt diets. Until attainment of the legal size for capture, survival was 9.6% higher on average, with extremes as low as 1.7% and as high as 38% in individual batches.     

Anemia and Growth Retardation in Totally Gastrectomized Swine

The effects of total gastrectomy in six young swine were followed and described during an experimental period up to 18 months. Two of the gastrectomized pigs (Nos. 1 and 2) were medicated with cycobemin every second week. Two other gastrectomized pigs (Nos. 11 and 14) were medicated with iron-dextran twice a week. Three non-gastrectomized swine receiving the same feed as the gastrectomized animals were observed as controls for up to eight months.One of the gastrectomized non-medicated pigs (No. 4) did not gain weight, while the other gastrectomized animals had a normal appearance and gained weight but less than the controls. The non-medicated as well as the cycobemin-medicated gastrectomized animals developed a microcytic hypochrome anemia corresponding to the anemia in iron deficiency. Histochemically loss of iron in the depots (liver, spleen, bone marrow and intestine) was demonstrated in the gastrectomized animals except those treated with iron-dextran. Histological and histochemical examinations of the nervous system did not show any abnormalities.