What accounts for the divergence between ranchers' WTA and WTP for public forage?

Results from a 2002 survey of Nevada ranchers that asked about willingness to pay for public forage and willingness to accept compensation to part with grazing rights provide empirical support for the contention of large divergence between WTA and WTP. WTA and WTP are estimated simultaneously, thereby enabling the identification of ranch characteristics that could explain the discrepancy in valuations. We find that some of the discrepancy might be explained by the size of a ranch's herd and the amount of public forage the ranch can access. We find little evidence that the ranching lifestyle accounts for the difference between WTP and WTA for public forage, as asserted by some ranch economists. It would appear that the discrepancy between WTA and WTP can be attributed primarily to an endowment effect.     

Effects of heavy metals on the litter consumption by the earthworm Lumbricus rubellus in field soils

Aim of this study was to determine effects of heavy metals on litter consumption by the earthworm Lumbricus rubellus in National Park the “Brabantsche Biesbosch”, the Netherlands. Adult L. rubellus were collected from 12 polluted and from one unpolluted field site. Earthworms collected at the unpolluted site were kept in their native soil and in soil from each of the 12 Biesbosch sites. Earthworms collected in the Biesbosch were kept in their native soils. Non-polluted poplar (Populus sp.) litter was offered as a food source and litter consumption and earthworm biomass were determined after 54 days. Cd, Cu and Zn concentrations were determined in soil, pore water and 0.01 M CaCl₂ extracts of the soil and in earthworms. In spite of low available metal concentrations in the polluted soils, Cd, Cu and Zn concentrations in L. rubellus were increased. The litter consumption rate per biomass was positively related to internal Cd and Zn concentrations of earthworms collected from the Biesbosch and kept in native soil. A possible explanation is an increased demand for energy, needed for the regulation and detoxification of heavy metals. Litter consumption per biomass of earthworms from the reference site and kept in the polluted Biesbosch soils, was not related to any of the determined soil characteristics and metal concentrations.     

Soil management effects on runoff and soil loss from field rainfall simulation

Soil erosion from agricultural lands is a serious problem on the Chinese Loess Plateau. In total, 28 field rainfall simulations were carried on loamy soils under different management practices, namely conventional tillage (CT), no till with mulch (NTM), reduced tillage (RT), subsoiling with mulch (SSM), subsoiling without mulch (SS), and two crops per year (TC), to investigate (i) the effects of different soil management practices on runoff sediment and (ii) the temporal change of runoff discharge rate and sediment concentration under different initial soil moisture conditions (i.e. initially dry soil surface, and wet surface) and rainfall intensity (85 and 170 mm h^− 1) in the Chinese Loess Plateau. NTM was the best alternative in terms of soil erosion control. SSM reduced soil loss by more than 85% in 2002 compared to CT, and its effects on runoff reduction became more pronounced after 4 years consecutive implementation. SS also reduced considerably the runoff and soil loss, but not as pronounced as SSM. TC resulted in a significant runoff reduction (more than 92%) compared to CT in the initial ‘dry’ soil, but this effect was strongly reduced in the initial ‘wet’ soil. Temporal change of runoff discharge rate and sediment concentration showed a large variation between the different treatments. In conclusion, NTM is the most favorable tillage practices in terms of soil and water conservation in the Chinese Loess Plateau. SSM can be regarded as a promising measure to improve soil and water conservation considering its beneficial effect on winter wheat yield.     

A factorial model to predict phosphorus waste output of rainbow trout (Oncorhynchus mykiss)

Minimizing phosphorus (P) wastes is considered to be a key factor for environmental sustainability of freshwater aquaculture operations in many parts of the world. A factorial P model, consisting of digestibility, whole-body P deposition, P waste output and limnological transformation sub-models, was constructed to simulate the effects of different dietary P sources and levels on P utilization in salmonids. This factorial P model was developed based on information from the literature for rainbow trout ( Oncorhynchus mykiss ). This factorial model runs on the platform of a fish bioenergetics model that provides dynamic estimates of feed intake of salmonids based on diet composition and growth rate. Simulations suggest that this model can potentially be a useful tool for waste output management of salmonid culture operations.     

Influence of vineyard location and vine water status on fruit maturation of nonirrigated cv. Agiorgitiko (Vitis vinifera L.). Effects on wine phenolic and aroma components

The influence of site on grape and wine composition was investigated for Vitis vinifera L. cv. Agiorgitiko in the Nemea appellation area in southern Greece. Three nonirrigated plots were studied during the 1997 and 1998 vintages, which were typically very hot and without summer rainfall. Vines were subjected to different water regimens as a result of the variation of soil water-holding capacity and evaporative demand. Vine water status was determined by means of predawn leaf water potential. Differences in vine water status between sites were highly correlated with the earliness of shoot growth cessation and veraison. Grape composition was monitored during fruit ripening. Water deficit accelerated sugar accumulation and malic acid breakdown in the juice. Early water deficit during the growth period was demonstrated to have beneficial effects on the concentration of anthocyanins and total phenolics in berry skins. A similar pattern was observed for the phenolic content of wines elaborated after vinification of grapes harvested on each plot, in both seasons. Limited water availability seemed to increase glycoconjugates of the main aromatic components of grapes as a quantitative increase in levels of bound volatile compounds of the experimental wines was observed under water deficit in both years. Wines produced from grapes of stressed vineyards were also preferred in tasting trials.     

Indications for both host-specific and introduced genotypes of Staphylococcus aureus in marine mammals

Staphylococcus aureus is present in the marine environment and causes disease in marine mammals. To determine whether marine mammals are colonized by host-specific strains or by strains originating from other species, we performed multi-locus sequence typing on ten S. aureus strains isolated from marine mammals in the U.K., the Netherlands, and the Antarctic. Four new sequence types of S. aureus were discovered. S. aureus strains from a southern elephant seal (n=1) and harbour porpoises (n=2) did not cluster with known S. aureus strains, suggesting that they may be host species-specific. In contrast, S. aureus strains from harbour seals (n=3), other harbour porpoises (n=3), and a grey seal (n=1) clustered with S. aureus strains previously isolated from domestic ruminants, humans, or birds, suggesting that these S. aureus strains in marine mammals were introduced from terrestrial species.     

Temporal changes of soil physical and hydraulic properties in strawberry fields

Even over short time intervals, soil properties are subject to variation, especially in managed soils. The objective of this study was to assess the temporal changes of soil physical and hydraulic properties in strawberry fields cultivated under surface drip fertigation in Turuçu, Brazil. Intact core samples were collected from the near surface soil layer of seedbeds to determine the total porosity (TP), macroporosity (MA), matrix porosity, bulk density (BD), available water capacity (AWC), field capacity, wilting point and Dexter’s S index. Aggregate samples were collected from the arable layer to determine the aggregate size distribution and aggregate mean weight diameter. All samples were collected from 15 strawberry fields and at four different times during the 2007–2008 strawberry growing cycle. Although soil pore‐solid relations are expected to adjust soon after seedbed construction, their variation was only evident after >13 weeks. Even though values of TP and MA decreased with time, and those of BD increased near the end of the growing cycle, all the soils maintained their capacity to support root activity as indicated by critical values of Dexter’s index (S > 0.03). The amount of relatively large aggregates (9.51–2.00 mm) and AWC increased towards the end of the strawberry cultivation cycle. With changes in soil structure improving soil physical quality, strawberry development benefitted. We showed that if farmers gradually increase the amount of water through fertigation to a maximum value occurring at the end of crop cycle instead of applying water at a constant rate, water and energy use efficiency in agriculture would improve.     

Effects of conservation agriculture on runoff,soil loss and crop yield under rainfed conditions in Tigray,Northern Ethiopia

The aim of conservation agriculture (CA) is to improve soil quality and crop yield whilst reducing runoff and topsoil erosion. An experiment was carried out in a rainfed field using a permanent raised bed planting system for 3 yr (2005–2007) in Adigudem, northern Ethiopia in order to evaluate the effect of CA on runoff, soil loss and crop yield. CA practices were introduced in fields with Vertisols in a randomized complete block design on permanent 5 × 19 m plots. Three treatments were evaluated: (1) conventional tillage (CT) with a minimum of three tillage operations and removal of crop residues, (2) terwah (TER) that was similar to CT except that contour furrows were included at 1.5 m intervals, and (3) derdero+ (DER+), which consists of permanent raised beds with a furrow and bed system, retention of 30% of standing crop residues and zero tillage on the top of the bed. All ploughing as well as the maintenance of the furrows of the permanent raised beds was done using a local ard plough called maresha. Results from monitoring over 3 yr showed that soil loss and runoff were significantly higher (P < 0.05) in CT followed by TER and DER+. Average soil losses of 5.2, 20.1 and 24.2 t/ha were recorded from DER+, TER and CT, respectively. Runoff was 46.3, 76.3 and 98.1 mm from DER+, TER and CT, respectively. Grain yield was significantly lower (P < 0.05) in DER+ under teff in 2006, probably due to the high sensitivity of teff to weeds. The yield of wheat in 2007 was significantly higher in DER+ followed by TER. The terwah system is recommended as a first measure for wider adoption to reduce runoff and soil loss and to increase crop yield. The long‐term goal is to achieve a derdero+ system, i.e. a permanent raised bed planting system along with the application of crop residues.     

Complexation of whey proteins with carrageenan

The formation of electrostatic complexes of whey protein (WP) and a nongelling carrageenan (CG) was investigated as a function of pH, ionic strength, temperature, and protein-to-polysaccharide (Pr:Ps) ratio. On lowering the pH, the formation of soluble WP/CG complexes was initiated at pH(c) and insoluble complexes at pH(phi), below which precipitation occurred. The values of the transition pH varied as a function of the ionic strength. It was shown that at [NaCl] = 45 mM, the value of pH(phi) was the highest, showing that the presence of monovalent ions was favorable to the formation of complexes by screening the residual negative charges of the CG. When CaCl(2) was added to the mixtures, complexes of WP/CG were formed up to pH 8 via calcium bridging. The electrostatic nature of the primary interaction was confirmed from the slight effect of temperature on the pH(phi). Increasing the Pr:Ps ratio led to an increase of the pH(phi) until a ratio of 30:1 (w/w), at which saturation of the CG chain seemed to be reached. The behavior of WP/CG complexes was investigated at a low Pr:Ps ratio, when the biopolymers were mixed directly at low pH. It resulted in an increase of the pH of the mixture, as compared to the initial pH of the separate WP and CG solutions. The pH increase was accompanied by a decrease in conductivity. The trapping of protons inside the complex probably resulted from a residual negative charge on the CG. If NaCl was present in the mixture, the complex took up the Na(+) ions instead of the H(+) ions.     

Comparing Aggregate Stability Tests for Soil Physical Quality Indicators

Although there is not a sole satisfactory methodology that applies universally up to now, aggregate stability has been proposed as an indicator of soil physical quality (SPQ). Difficulties persist when comparison of aggregate stability from different procedures are performed. The objective of this study is to evaluate appropriate aggregate stability methods that enable to distinguish the SPQ condition of both temperate and tropical medium‐textured soils. Among different methods tested, results show that wet sieving using the well known fast wetting methods of Kemper & Rosenau and of Le Bissonnais rendered similar results in both environments. The mean weight diameter value of both methods for assessing aggregate stability can be considered as a dependable indicator of soil structure status for comparing soils. These aggregate stability methods are in correspondence with only one out of the eight SPQ indicators when entirely soils were used. It was concluded that the aggregate stability should be used judiciously and in concert with other indicators for an overall assessing of the SPQ condition. Copyright © 2013 John Wiley & Sons, Ltd.