Estimates of residual dairy manure nitrogen availability using various techniques

It is common practice to repeatedly apply dairy manure to the same fields. To accurately assess the total plant availability of manure nutrients, it is necessary to account for the nutrients remaining in soil from previous manure applications. A field experiment studying manure nitrogen (N) uptake by corn (Zea mays L.) was conducted from 1998 to 2003 on a Plano silt loam (fine-silty, mixed, mesic, Typic Argiudolls). Plots received two rates of semisolid manure either every year, every 2 yr, or every 3 yr to estimate first-, second-, and third-year dairy manure N residuals. Residual manure N availability was estimated from single and multiple manure applications using (i) the fertilizer N equivalence method, (ii) the apparent recovery (difference) method, (iii) relative effectiveness method, and (iv) recovery of (15)N-labeled manure. Second-year availabilities after a single manure application using the fertilizer equivalence, difference, and relative effectiveness methods were estimated to be 12, 8, and 4% of total manure N applications, respectively. Estimates of third-year availability by these methods were 3, 1, and 5%, respectively. Measurement of (15)N recovered from labeled manure was 6 and 2% in the second and third year, respectively. Fertilizer equivalence, difference, and relative effectiveness methods showed great year to year variability, reducing the confidence in the residual manure N availability estimates by these methods, but using (15)N-labeled manures reduced variability substantially. Based on this and other studies, we suggest that second- and third-year residual N availability from a single application of semisolid dairy manure would be 9 to 12%, and 3 to 5% of the original manure N application, respectively.     

Patterns of Giving and Receiving Help During Severe Winter Conditions: A Research Note

Severe winter conditions and blizzards may cause persons to be stranded, unable to move from one place to another. Being stranded under such conditions can be life-threatening and often requires help. This is a study of giving and receiving help among people who were stranded during severe winter conditions and blizzards in Bowling Green, Ohio, USA and the surrounding countryside in 1976–1977. Mail questionnaire data were collected from the Bowling Green, Ohio telephone directory which included listings from both rural and urban areas. The family, followed by friends and neighbors, were most important in the giving and receiving of help. There was little difference between the responses of rural and urban residents. Propinquity was found to be an important intervening variable.     

Movement of oxybiotic and thiobiotic meiofauna in response to changes in pore-water oxygen and sulfide gradients around macro-infaunal tubes

The effects of changes in vertical and horizontal microscale gradients of oxygen and sulfide on meiofaunal distributions were examined in laboratory microcosms. Specifically, the effect of tube abandonment and reestablishment by macro-infauna on the distribution of subsurface turbellarians, gnathostomulids and gastrotrichs was studied. Meiofauna responded rapidly (within 6 h) to changing sediment chemistry, consistently trying to reoccupy optimal habitat. Every subsurface taxon had a preferred suboptimal habitat which it occupied primarily during transit from deteriorating to newly established optimal habitat. Only during this time did the distribution of ecologically similar taxa overlap substantially. Changes in oxygen and sulfide gradients could explain most but not all of the response; food availability might also be important. Oxybios consistently chose oxic suboptimal microhabitat. Thus behaviorally, as well as biochemically and ecologically, thiobios represent a distinct group among the meiofauna.     

Acclimation of the European sea bass to freshwater: monitoring genetic changes by RAPD polymerase chain reaction to detect DNA polymorphisms

We investigated the use of the polymerase chain reaction (PCR) and the associated random amplification of polymorphic DNA (RAPD) technique to study variation in samples of the sea bass, Dicentrarchus labrax, before and after acclimation to freshwater. Acclimation trials were repeated twice, in 1989 and 1990, for two samples originating from the same broodstock (individuals from different localities along the Italian coasts), with overall mortality rates averaging 94 and 75% in the 2 yr, respectively. Analyses are based on 126 polymorphic RAPD markers, scored in at least 39 individuals for each of the starting and acclimated samples in both years. Analysis of RAPD patterns revealed high levels of DNA polymorphism in both 1989 and 1990 starting samples. The acclimated samples maintained similar polymorphism levels. Shifts in marker frequencies between starting and acclimated samples occurred in both years. A correspondence analysis carried out on multimarker individual profiles suggests that the two starting samples resulted from uneven sampling of the same heterogenous broodstock. This analysis clearly separates RAPD phenotypes from starting and acclimated samples in both years and identifies the RAPD markers responsible for such displacement. Patterns of RAPD variation are compared with previous allozymic studies carried out on the same samples. A major difference between the two studies was the number of markers available. Fewer allozyme loci were studied than were RAPD markers. The cause of repeated shifts for allozyme alleles in replicate experiments were almost certainly due to selection, while statistical chance could explain the repeated shift of only one out of more than 100 RAPD markers. We have shown that RAPD analysis, if carried out carefully, is quite reproducible and sensitive enough to reveal high levels of variation among individuals from the same broodstock. A major drawback of this approach is the still unclear inheritance patterns of RAPD polymorphisms. The use of multivariate analyses is suggested as a possible alternative to traditional population genetics techniques to analyze patterns of variation in the absence of a precise genetic interpretation.     

Chromium uptake by rice and accumulation in soil amended with municipal solid waste compost

Effect of addition of municipal solid waste compost (MSWC) on chromium (Cr) content of submerged rice paddies was studied. Experiments were conducted during the three consecutive wet seasons from 1997 to 1999 on rice grown under submergence, at the Experimental Farm of Calcutta University, India. A sequential extraction method was used to determine the various chromium fractions in MSWC and cow dung manure (CDM). Chromium was significantly bound to the organic matter and Fe and Mn oxides in MSWC and CDM. Chromium content in rice straw was higher than in rice grain. Chromium bound with organic matter in MSWC best correlated with straw Cr (r=0.99**) followed by Fe and Mn oxides (r=0.97*) and water soluble as well as exchangeable fractions (r=0.96*). The water soluble and the exchangeable fractions in MSWC best correlated with grain Cr (r=0.98*). The Cr content of rice grain had the highest correlation with water soluble and exchangeable Cr (r=0.99**) while the straw Cr best correlated with the Fe and Mn oxides (r=0.98*). Both the carbonate bound and residual fractions in MSWC and CDM did not significantly correlate with rice straw and grain Cr. MSWC would be a valuable resource for agriculture if it can be used safely, but long-term use may require the cessation of the dumping by the leather tanneries and other major contributors of pollutants.     

Yield and nutritive quality of sericea lespedeza (Lespedeza cuneata) and little bluestem (Schizachyrium scoparium) exposed to ground-level ozone

Sericea lespedeza (Lespedeza cuneata cv. Interstate 76) and little bluestem (Schizachyrium scoparium cv. Aldous) were raised from seed in a glasshouse, transplanted into 5.7-l pots and placed into open-top chambers (OTC) on 6 June 1999. Following a 7-day adjustment period, each of six OTCs (duplicate OTCs per treatment) was ventilated with either air that had been carbon-filtered (CF) to remove ambient ozone (O3); non-filtered (NF), representative of ambient air; or enriched to twice-ambient O3 concentration (2X). Primary-growth forage was harvested on days 7, 32, 46, 59 and 72 following the start of fumigation, and regrowth forage from the first primary-growth harvest was harvested on days 36, 54 and 72 following the start of fumigation. Dry matter (DM) yield of either forage species did not differ among treatments except in the final regrowth period when yield of sericea lespedeza was greater for the NF than 2X O3 treatment. In vitro DM digestibility (IVDMD) and concentrations of crude protein (CP), soluble phenolics (SP) and condensed tannins (CT) in primary-growth sericea lespedeza did not differ between treatments, but NF primary-growth forage had higher concentration of protein-precipitating tannins (PPT) than did 2X primary-growth forage. Concentrations of neutral detergent fiber (NDF), acid detergent fiber (ADF) and acid detergent lignin (ADL) were higher in NF and 2X than in CF primary-growth sericea lespedeza. Similarly, concentrations of NDF and ADL were higher, and IVDMD was lower for NF and 2X than for CF regrowth sericea lespedeza. Concentrations of ADF and ADL were lower, whereas IVDMD, in vitro NDF digestibility (IVNDFD) and concentrations of CP and SP were greater, in CF than in NF and 2X primary-growth little bluestem. Percentages IVDMD and IVNDFD and concentrations of CP and SP in NF primary-growth little bluestem were greater than those in forage exposed to 2X O3 treatment. No significant differences were observed among treatments in percentages IVDMD and IVNDFD, or concentrations of cell wall constituents or SP in little bluestem regrowth. Nutritive quality of little bluestem was decreased by < 2%, and that of sericea lespedeza by approximately 7% as a result of increased concentrations of cell wall constituents and decreased in vitro digestibility of NF and 2X compared with CF forages. Results indicate that existing and projected O3 levels can drive alterations in forage quality of select warm-season forages sufficient to have nutritional and economic implications for their utilization by ruminant herbivores.     

Phylogenetic relationships within the class holothuroidea,inferred from 18S rRNA gene data

This molecular phylogenetic analysis of 18S ribosomal RNA (18SrDNA) gene sequences from 16 species of holothuroid, suggests strong support for an alternative taxonomic scheme to replace the existing classification. When trees drawn from the 18S rDNA data were constrained to show expected relationships between the holothourid orders, they were significantly worse than the best tree under SH tests. These analyses indicated strongly that the subclass Aspidochirotacea is paraphyletic. Sequences from the order Dendrochirotida grouped with aspidochiroitid sequences, with high bootstrap support, to the exclusion of the elasipod sequence. In line with recent morphological studies the order Apodida were a basal sister group to the other three holothuroid orders examined and the Dendrochirotida was a derived holothuroid order. Brendan F. Keegan, Richard Powell: R.I.P     

Balancing Forest‐Regeneration Probabilities and Maintenance Costs in Dry Grasslands of High Conservation Priority

Abstract: Abandonment of agricultural land has resulted in forest regeneration in species‐rich dry grasslands across European mountain regions and threatens conservation efforts in this vegetation type. To support national conservation strategies, we used a site‐selection algorithm (MARXAN) to find optimum sets of floristic regions (reporting units) that contain grasslands of high conservation priority. We sought optimum sets that would accommodate 136 important dry‐grassland species and that would minimize forest regeneration and costs of management needed to forestall predicted forest regeneration. We did not consider other conservation elements of dry grasslands, such as animal species richness, cultural heritage, and changes due to climate change. Optimal sets that included 95–100% of the dry grassland species encompassed an average of 56–59 floristic regions (standard deviation, SD 5). This is about 15% of approximately 400 floristic regions that contain dry‐grassland sites and translates to 4800–5300 ha of dry grassland out of a total of approximately 23,000 ha for the entire study area. Projected costs to manage the grasslands in these optimum sets ranged from CHF (Swiss francs) 5.2 to 6.0 million/year. This is only 15–20% of the current total estimated cost of approximately CHF30–45 million/year required if all dry grasslands were to be protected. The grasslands of the optimal sets may be viewed as core sites in a national conservation strategy.