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Farm soil tests are common decision support tools employed by regulatory agencies and farmers to manage nutrients in an economical and environmentally sustainable way. The complex interplay between the local environment and locally relevant crops makes soil testing, and critically soil-test-based recommendations, site-specific. Newfoundland and Labrador has a relatively small but rapidly growing commercial agriculture industry, mainly on lands converted from the boreal forest over the last 80 yr. A first step towards developing locally calibrated fertilizer recommendations is understanding current practices. For this, we examined regular farm soil test reports and associated recommendations for Newfoundland (Nfld). Following a request distributed to 167 farmers, 1503 soil tests were obtained from 32 farms. Although tests exemplify the gamut of crops in Nfld, more than half were from forage and mixed forage fields in western Nfld, representing dairy farms. Results show that even in the absence of more comprehensive site analyses, an investigative survey of farm tests may be employed to recognize possible environmental and economic inefficiencies of local cropping systems, including regional and crop type-driven differences for both nitrogen (N) and phosphorus (P) fertilizations. Soil-test-based identification of possible N and (or) P inefficiencies and associated crop and regional particularities, including excess fertilization, can be employed to devise targeted research for improved, preventative decision tools to increase the sustainability of Nfld agricultural systems.

Craniopharyngiomas (CPs) are benign tumors arising from the sellar region. However, little is known about their clinical features and long-term recurrence due to low morbidity and the lack of large cohort studies. Thus, we aimed to develop nomograms to accurately predict the extent of resection and tumor recurrence using clinical parameters. A total of 545 patients diagnosed with CP between 2009 and 2019 were examined: 381 in the development cohort and 164 in the validation cohort. Least absolute shrinkage and selection operator (LASSO) and Cox regression analyses were performed to establish two nomograms. Receiver operating characteristic (ROC) curves, calibration curves, decision curve analysis (DCA) and Kaplan-Meier (KM) curves were used to evaluate their predictive performance and discriminative power, respectively, in the two cohorts. In addition, the EORTC QLQ-BN20 questionnaire was used to assess neuropsychological status in the follow-up. In the development cohort, the area under the curve (AUC) and C-index were 0.760 and 0.758, respectively, for predicting the extent of resection and 0.78 and 0.75, respectively, for predicting 3-year progression-free survival (PFS) and 5-year PFS. Additionally, the model had a predictive accuracy of 0.785. Both nomograms showed acceptable discrimination in the two cohorts. Moreover, DCA demonstrated excellent clinical benefits from the two nomograms. Finally, participants were classified into two distinct risk groups according to the risk score, and an online calculator was created for convenient clinical use. During long term follow-up, hypothyroidism (77.61%) and hypocortisolism (76.70%) were the most common endocrine dysfunction after surgery and significant deficits were observed concerning visual disorder, motor dysfunction and seizures in the recurrent groups. In particular, better quality of life was associated with gross total resection (GTR), postoperative radiation, anterior interhemispheric (AI) approach and transsphenoidal approach. To our knowledge, these are the first nomograms based on a very large cohort of patients with CP that show potential benefits for guiding treatment decisions and long-term surveillance. The current study demonstrated the online calculator serve as the practical tool for individual strategies based on the patient’s baseline characteristics to achieve a better prognosis.

In the USA, western Washington (WWA) and the Alaska (AK) Interior are two regions where maritime and continental climates, high latitude and cropping systems necessitate early maturing spring wheat (Triticum aestivum L.). Both regions aim to increase the production of hard spring bread wheat for human consumption to support regional agriculture and food systems. The Nordic region of Europe has a history of breeding for early maturing spring wheat and also experiences long daylengths with mixed maritime and continental climates. Nordic wheat also carries wildtype (wt) NAM-B1, an allele associated with accelerated senescence and increased grain protein and micronutrient content, at a higher frequency than global germplasm. Time to senescence, yield, protein and mineral content were evaluated on 42 accessions of Nordic hard red spring wheat containing wt NAM-B1 over 2 years on experimental stations in WWA and the AK Interior. Significant variation was found by location and accession for time to senescence, suggesting potential parental lines for breeding programmes targeting early maturity. Additionally, multiple regression analysis showed that decreased time to senescence correlated negatively with grain yield and positively with grain protein, iron and zinc content. Breeding for early maturity in these regions will need to account for this potential trade-off in yield. Nordic wt NAM-B1 accessions with early senescence yet with yields similar to regional checks are reported. Collaboration among alternative wheat regions can aid in germplasm exchange and varietal development as shown here for the early maturing trait.

Managing a robust pasture ecosystem and optimizing available forage under sub-arctic conditions in interior Alaska is a challenge. The region is characterized by a short growing season, slow residue decomposition rates and undeveloped soils that are vulnerable to compaction and erosion. The goal of this research was to examine the relative and combined role of grazing mechanisms; herbivory, trampling, and manure/urine deposition on forage yield and soil health in sub-arctic pastures within a simulated intensively managed rotational grazing (IMRG) framework. A full factorial experiment of muskox (Ovibos moschatus) manure/urine deposition (M), simulated trampling (T), and herbivory (forage clipping) (H), and control (C) mimicking IMRG timing and intensity, was conducted at the Robert G. White Large Animal Research Station, University of Alaska, Fairbanks. The simulations were conducted on 48–1 m2 plots on hilltop and hill bottom pastures with different vegetation and soil types, over the 2014 and 2015 grazing seasons. The control represented a pasture absent of grazing and served as a comparison of the treatments to restorative rest of grazing land. Grazing treatments MH and MTH had a positive impact on forage yield, while T and MT had a negative impact compared to C (p

Thermokarst (thaw) lakes are an important source of atmospheric CH4; however, few studies have examined the composition and biodegradability of their sediment organic matter (OM). We have quantified the (i) composition of bulk sediment OM (bulk SOM) using pyrolysis gas chromatography-mass spectrometry (GC-MS) and (ii) statistical relationships between bulk SOM properties and anaerobic incubation CH4 production rate at 3 °C in sediment core samples from a thermokarst lake system. The study extended through the full vertically-thawed profile (0–550 cm) of Vault Lake, a small thermokarst lake near Fairbanks, Alaska, USA, and into the permafrost thawing beneath the lake (551–590 cm). Compared with the underlying mineral-dominated sediments (153–590 cm depth in core), the surface organic-rich sediment horizon (0–152 cm) had higher CH4 production rate, greater substrate availability indicated by percent organic carbon and total nitrogen, and greater proportions of terrestrially-associated bulk SOM compounds (alkanes, alkenes, lignin products, and phenols and phenolic precursors). Correlation and principal component analyses indicated that CH4 production potential values measured in the core were positively associated with initial substrate availability and terrestrially-derived OM compounds. We observed positive correlation (p ⩽ 0.05) between CH4 production and bulk SOM compounds classified as phenols and phenolic precursors, a pattern different from previously observed relationships in natural aquatic anaerobic environments.

Water extractable organic carbon (WEOC) and nitrogen (WEON) are two key parameters of soil water extractable organic matter (WEOM). Proper management of manure application rate in combination with tillage and cropping management could maintain appropriate WEOC and WEON concentrations in soils while decreasing the risk of their runoff from cropland and pastures. The objective of this research was to determine the effect of poultry litter (PL) application on WEOC and WEON in soils under different crops, tillage regimes, and grazing strategies. From 2001 to 2012, PL was applied at multiple rates to cultivated fields in a corn-oat/wheat-hay rotation or to pastures grazed by cattle or ungrazed. Soil samples (0 - 15 cm) were analyzed for KCl-extractable mineral N, and WEOC, and WEON contents. In addition, Ultraviolet-visible (UV-vis) and fluorescence spectroscopies were used to characterize WEOC stability. Organic N levels were higher at the high PL application rates. The soil C:N ratio narrowed as the PL application rate increased. However, the soil from pastures which received PL tended to have a wider range of C:N ratios than soil from the cultivated fields, despite identical PL application rates. The spectral analyses indicated that WEOC properties were responsive to management and PL application rate; therefore, this parameter may be used as a guide to provide best management strategy for manure application.

Barley has been a mono cereal crop grown in the Delta Junction area of Alaska since 1970s. A rotational crop is needed for weed control and conservation tillage for sustainable crop production. Due to short growing season constrains, canola when used as a rotational crop currently resulted low marketability because of high green seed content (>2%). The objective of this research is to determine if glyphosate when used as a desiccating chemical could promote early maturity and reduce green seed content of canola. Four Polish canola cultivars were treated with direct combine (as a control), pushing (to stop growth) and desiccating in two locations in Alaska USA in a randomized complete block design with four replicates from 2007 to 2009. Glyphosate was sprayed, and pushing was conducted around August 15 each year. Results showed that 'Hysin 110' treated by glyphosate consistently had ≤ 2% green seed content in three years in contrast with 'Reward' despite a wide variation of weather conditions. The growing degree days were dramatically different among the three years, with 2009 close to the 29-year norm, 2008 was lower and 2007 was higher than the norm. No residual glyphosate was found in the seeds from the desiccating treatment. In conclusion, desiccating treatment together with a good short growing season Polish canola cultivar can make canola grown as a rotational crop in Alaska’s short growing season conditions.

Sequential fractionation coupled with phosphatase hydrolysis allows a greater understanding of the effects of animal manure on the chemical distribution of soil P. Concentrations of specific soil P fractions were determined after long-term (>10 yr) poultry litter application at rates of 4.5, 6.7, 9.0, 11.2, and 13.4 Mg manure ha⁻¹ yr⁻¹ to watershed-scale plots (cultivated and grazed–ungrazed pasture) on a calcareous Texas Blackland Vertisol. Soil total extractable P (Pₜ) and inorganic P (Pᵢ) were quantified following sequential extraction with H₂O, NaHCO₃, NaOH, and HCl. Hydrolyzable organic P (Pₑ) and non-hydrolyzable organic P (Pₙₑ) were determined in the extracted fractions following enzymatic hydrolysis. Litter application increased Pₜ regardless of land-use type compared with the control. Concentrations of H₂O-extractable Pᵢ in litter-amended plots increased by 9 to 34% (cultivated) and 7 to 30% (pasture) over the control, indicating substantial risk of soluble P runoff. Labile organic P (Pₒ) extracted with H₂O and NaHCO₃ decreased in the order monoester > nucleic acid > phytate > Pₙₑ. An average of 68% of Pₜ was extractable with HCl. Organic P comprised the majority (95%) of HCl-Pₜ; however, only trace levels of HCl-Pₒ were hydrolyzable, and litter application increased HCl-Pₙₑ up to 217%. Thus, litter application increased levels of both soluble Pᵢ and stable Pₙₑ, but the specific response varied with application rate and land management. This study increased understanding of P chemical distribution with time in litter-amended soil with high clay and CaCO₃ contents under differing land-use scenarios.

Non-cohesive soils are extensively distributed in Interior Alaska and soil erosion in a newly constructed roadside embankment is of great concern. Geofibers and nontraditional additives have been used for stabilizing non-cohesive soils and controlling soil erosion. However, in cold regions where permafrost exists such as Interior Alaska, any erosion control measures in a newly constructed roadside embankment must also allow a vegetation establishment at the same time, to mitigate potential permafrost degradation caused by surface modifications. Literature review indicates that no previous research has been done to consider both effects. There is a great need to investigate if geofibers and nontraditional additives can be used in Interior Alaska for soil erosion control and permafrost degradation mitigation. This paper presents the laboratory and field test results on use of geofibers and nontraditional additives (synthetic fluid and polymer emulsion) to control soil erosion in Interior Alaska. Locally available non-cohesive soils were used as a control and compared with the same soils treated with different doses of geofibers and nontraditional additives, including: 1) 4% synthetic fluid and 0.5% geofibers, 2) 2% polymer emulsion + 0.5% geofibers, 3) 2% polymer emulsion, and 4) 0.5% geofibers only. The results on soil critical shear stresses, sediment collections, soil organic matter, and plant available nutrients were analyzed from which some conclusions were made regarding working mechanisms of the geofibers and two nontraditional additives on soil erosion control in Interior Alaska.

Very limited information is available on the impacts of organic farming practices on the chemical composition and properties of dairy manure. In this study, we found the differences in the absorptivities of dissolved organic matter between conventional and organic dairy manure samples at 254 and 280 nm, reflecting the difference in aromaticities of dissolved organic matter of the manures. The 13C nuclear magnetic resonance (NMR) characteristics of triple peaks around 30 ppm were more evident in organic samples than in conventional dairy manure samples. This observation was presumably due to more forage feedstuff used in organic dairy farms as this spectral feature was assigned to cutin and cutan from the outer cuticle of herbaceous plants. Thus, the distinct NMR feature of manure around 30 ppm, if further confirmed, can serve as a traceable forage marker to evaluate the authenticity of organic dairy farming programs.

Emission of windblown dust and PM10 (particulates ≤10 μm in diameter regulated by many nations as an air pollutant) from agricultural soils can impact regional air quality. Little information exists that describes the potential for PM10 and airborne dust emissions from subarctic soils or agricultural soils subject to different tillage and residue management. This study documents the influence of tillage and residue management on fine particulate emissions from a subarctic soil in Interior Alaska. Surface characteristics and properties of a silt loam soil subject to conventional, spring disk, autumn chisel plow, and no tillage, with stubble and loose straw retained or removed from the soil surface after harvest of continuous barley (Hordeum vulgare L.), was measured twenty years after establishing treatments. These soil characteristics and properties were used to simulate PM10 emission potential and soil loss from tillage and residue treatments using the Single-event Wind Erosion Evaluation Program (SWEEP). Primary particle size analysis indicated no statistical difference in the size of primary soil particles among tillage or residue treatments. Aggregate size distribution analysis showed that tillage affected the freely-available PM10 content of the soil in the field. No tillage resulted in the lowest freely-available PM10 content as compared with other tillage treatments. Simulations made with SWEEP suggest that PM10 emissions and soil loss are potentially highest for conventional tillage and lowest for no tillage while emissions and soil loss were lower from spring disk than autumn chisel plow. Tillage practices can therefore affect air quality and long range transport of fine particulates emitted into the atmosphere during high wind events in subarctic Alaska.

Cold (22 oC) and hot water (80 oC) extractions have been used to estimate labile organic carbon (C) and nitrogen (N) in soils. Sequentially extracted cold and hot water organic matter (WEOM) from 14 Alaskan soils under different land uses were characterized by ultraviolet and fluorescence spectroscopies. Compared to cold WEOM, the ultraviolet (UV) absorptivity at 254 nm and fluorescence index were significantly (P < 0.05) decreased in hot WEOM of all soils. The biodegradability, assessed in a 21-d solution incubation, of hot WEOC and WEON was significantly (P < 0.05) greater than that of cold WEOC and WEON in all soils. The biodegradability of cold or hot WEOC was correlated with the protein-like component, indicating that a protein-like fluorophore is a labile fraction in both cold and hot WEOM pools. Information derived from this work contributed to better understanding of subarctic soil WEOM properties and their biodegradability.

Laxiwa Hydropower Station is the largest among those hydropower stations in the upper reaches of the Yellow River. The construction started in October 2001, diversion tunnel was finished in January 2004, and impoundment started in March 2009. However, from May 2009, the right-bank slope of the reservoir about 700 m high and 1, 000 m wide located 500 m far from the dam was found to be deforming greatly and continuously. Although this slope had been identified as an old landslide, the survey before the construction of the dam concluded that this slope being composed of granite is stable and would be stable even after the impoundment, and thus no detailed monitoring of the slope deformation had been performed before the visible deformation occurred after the impoundment. To indentify the relationship between the deformation of the slope and impoundment, we utilized differential synthetic aperture radar interferometry and Advanced Land Observing Satellite Prism data to analyze the slope deformation before and after impoundment. We found that no identifiable deformation took place before the impoundment, while during the period of 3 April 2009 to 22 May 2010, after impoundment, maximum horizontal displacement reached approximately 7.5 m. This slope is still deforming even after a total horizontal displacement of several tens of meters being reached, showing high risk of catastrophic failure.

Most fertilizer phosphorus (P) rate recommendations for the north-central United States are based on combination of a critical soil-test P value and a mass-balance calculation of fertilizer P required to maintain critical soil-test P. Accurate estimates of grain P removal are an essential component of P mass-balance calculation. Current north-central extension service guidelines recommend that estimates of corn and soybean grain P removal should be calculated using constant grain P concentrations. We reviewed research from the north-central region to determine the extent to which variation in grain P concentration accounts for differences in crop P removal and to determine whether predictions of grain P concentration can be improved through consideration of soil-test P, crop yield, and fertilizer P application. We found that soil-test P, grain yield, and fertilizer P are predictor variables that may significantly improve estimates of grain P concentration for corn and soybeans.

Aminopyralid is used in Alaska to control certain invasive weed species; however it appears to have an extended soil half-life in interior Alaska resulting in carry-over injury in potatoes. Field studies at three experiment stations in Delta Junction, Fairbanks, and Palmer, Alaska were established to determine the dose–response of weeds and above and below ground potato growth to soil-applied aminopyralid (0, 8, 15, 31, 62, and 123 g ae ha−1) . Both prostrate knotweed and narrowleaf hawksbeard were susceptible to aminopyralid. At Delta Junction and Fairbanks, visual injury of potatoes greater than 25 % was observed at 15 g ae ha−1 aminopyralid, whereas at Palmer visual injury was greater than 40 % at 8 g ae ha−1, the lowest rate tested. Potato tuber production was reduced by aminopyralid at rates of 15 g ae ha−1 and above at both Delta Junction and Palmer. Sub-samples of potato tubers from Delta Junction and Palmer were analyzed for aminopyralid content and grown out to determine if aminopyralid in tubers would reduce subsequent growth. The aminopyralid concentration in potato tubers increased with increasing field application rates, with 30 ppb extracted from tubers grown at the highest application rate (123 g ae ha−1). All plants grown from daughter tubers except from control plots in Palmer exhibited injury symptoms. The number of emerged shoots, and shoot height decreased with increasing aminopyralid concentrations in the tuber, with injury rates greater than 70 % at 8 g ae ha−1.

Land use conversion induces quantitative change of soil water-soluble organic matter (WSOM), but knowledge of such change is still limited. In this study, field moist and air-dried soils sampled from subarctic Alaska under three land use managements (i.e., forest, agriculture, and grassland converted from agricultural use and under a Conservation Reserve Program [CRP]) were extracted with deionized water and separated by filtration into different size fractions (2.5 μm, 0.45 μm, and 1 kDa). Water-soluble organic C (WSOC), water-soluble organic N, and fluorescence spectroscopy of each fraction were determined. There were few differences in quantitative data between samples from different land uses with air-dried samples, implying that air-dried samples were not suitable for characterizing the impact of soil management practices on soil WSOM. For field moist soil samples, the WSOC contents decreased in the order forest > CRP > agricultural land. Furthermore, WSOC was dominated by large (>0.45 μm) and small (

This work evaluated the level and nature of water-extractable soil organic matter (WEOM) from a 6-yr potato ( L.) crop rotation field experiment. The content of WEOM was higher in continuous potato soils than in the 2-yr and 3-yr crop rotation soils except for those crop rotation soils with soil improvement management by composted manure. Irrigation increased the level of WEOM in crop rotation soils. Ultraviolet–visible and fluorescence parameters indicated that WEOM in continuous potato soil possessed a high degree of humification and that crop rotation increased the aromatic and low molecular mass portions. In most irrigated soils, WEOM contained less aromatic but higher humified components. Characterization of the WEOM samples with crop rotation and irrigation suggests that these management practices stimulate the decomposition of the humic fraction in soil organic matter pools, implying healthier soil conditions with these management practices than with continuous potato growth.

Insect herbivory can produce a pulse of mineral nitrogen (N) in soil from the decomposition of frass and cadavers. In this study, we examined how diet quality affects rates of N and carbon (C) mineralization from grasshopper frass and cadavers. Frass was collected from grasshoppers fed with natural or meridic diets which varied in N content. Frass was also collected from naturally foraging grasshoppers. Nitrogen concentration of frass was directly proportional to diet N, but N content of cadavers was not affected by diet. Incubations of soil plus frass were performed at constant soil moisture and temperature (15°C) for 28 days, after which levels of mineral N (KCl extract) were determined. About 44 % of C and N from the cadavers were mineralized after the 28-day incubation. Carbon mineralization of frass was not affected by diet or frass N but varied considerably among different food treatments: from 15 to 46 % of the C in frass was released as carbon dioxide. Generally, frass with C/N ratio greater than 20 resulted in net immobilization of N. Results suggest that much of the N in grasshopper frass and cadavers is labile and rapidly available for plants, depending on the quality of food consumed by the grasshoppers.

As the demand for food, feed, fiber, and, most recently, bio-energy increases, more land may be converted from native conditions for arable uses. Our objective was to evaluate soil quality under native forest, arable land being used for continuous barley (Hordeum valgare L.) production and land that had been tilled and subsequently enrolled in the Conservation Reserve Program (CRP) for at least 18 years. Several physical, chemical, and biological soil quality indicators were measured and a soil deterioration index (DI) was calculated using forest soil as the reference. Results indicated that most organic matter under forest resided on soil surface and was not mixed with mineral soil due to lack of activities by large soil fauna (e.g., earthworms). Soil samples from disturbed areas had a higher organic matter content, which caused most soil quality indicators to be considered ‘improved’ and resulted in better DIs for agricultural and CRP land than for forest soils. This study emphasized the importance of c...

Sequential fractionation is a common method used in eval­ uating the impacts of soil management practices on soil phosphorus (P) distribution. However, to our knowledge, this method has not been used in investigating the effects of irrigation on the changes in soil P fractions. In this work, we measured sequentially extracted P by deionized H20, 0.5 M sodium bicarbonate (pH 8.5), 0.1 M sodium hydroxide (NaOH), and 1 M hydrochloric acid (HCI) in Caribou sandy loam soil samples from 10 potato fields under different 3-year crop rotations both with and without irrigation. As inorganic fertilizer was applied to these fields, irrigation and rotation management practices mainly affected the dis­ tribution of inorganic P fractions, but had no significant changes of organic P fractions. The impact of crop rotation was mainly reflected by H20-extractable P Irrigation had greater influence on stable or re­ calcitrant P in NaOH, HCI, and residual fractions. Higher levels of NaOH-extractable inorganic P were observed in soil from rainfed fields, whereas higher levels of HCI-extractable P were observed in soils under irrigated management. Our data indicate that irrigation may eventually decrease P availability and runoff potential in these potato soils over the long term because of the partial transfer of P in the sink from the active NaOH fraction to more stable HCI and residual fractions. Whereas in­ formation and knowledge derived from this study may shed some light on the transformation mechanism of soil P fractions for sustainable agri­ cultural production, more field data from shortand long-term experiments are needed to confirm our observations.

In some systems, grasshoppers appear to be food limited in most years, whereas in other systems top down forces, for example, predators, are more often implicated in population regulation. Sustainable strategies to manage grasshopper populations through habitat management require knowledge of the forces that regulate grasshopper populations. This experiment was undertaken to determine whether populations of Melanoplus borealis (Fieber), a common pest species in Alaska, are food-limited in Alaska. Cages were set up in a fallow field near Delta Junction, AK, in 3 yr (2007-2009). In 2007 and 2008, fertilizer was added to half the plots to increase primary production, and, in all years, cages within each plot were stocked with 0, 5, 9, or 13 fourth-instar M. borealis (equivalent to 0, 20, 36, or 52 grasshoppers/m(2)). Grasshoppers in each cage were counted weekly. Near the end of the growing season, surviving female grasshoppers (≈40% of the original number) were collected. Femur length was taken as a measure of adult size, and functional ovarioles were counted as a measure of current fecundity. If the grasshoppers were food limited, we expected to see significant effects of either density or fertilizer on grasshopper survival, size, or fecundity. The fertilizer treatment greatly increased primary production in both years. Neither fertilizer treatment nor grasshopper density had consistent effects on survival, size, or potential fecundity, leading us to conclude that food is seldom limiting to populations in the interior of Alaska at densities50 m(-2).

Water-extractable organic matter (WEOM) contains labile organic carbon (C) and nitrogen (N) and is sensitive to soil management. The objective of this study was to determine the quantity and spectral properties of soil WEOM responding to types of nutrient addition and tillage managements. Soil samples were taken from treatments (con- ventional tillage, no-tillage, poultry litter, and NH4NO3 application) of a 10-year experiment in Watkinsville, Georgia, at different times and soil depths. Air-dried soil samples were extracted by deionized water followed by filtration (G0.45 Km), and soluble C and N, absorptivity at 254 nm, and fluorescence excitation/emission matrix in the extract were determined. Results showed that poultry litter application accumulated higher amounts of water-extractable organic C and N than NH4NO3 application. But no significant difference was found between tillage and no-tillage for both water-extractable C and N. Absorptivity at 254 nm decreased during cropping years for conventional tillage and NH4NO3 application, indicating accumulation of aliphatic organic compounds in WEOM, but the fluorescence-measured humification index showed an opposite trend. For no-tillage and poultry litter application treatments, there was no difference in absorptivity over the sampling time. Parallel factor analysis of excitation/emission matrix data showed that WEOM consisted of three fluorophore components: humic-, fulvic-, and tyrosine- like ''compounds,'' and relative distribution of these components differed among treatments and changed over soil depths. The tyrosine-like com- ponent tended to accumulate in the lower sampling depth (915 cm). Overall, the quantity and spectral properties of WEOM responded to the types of nutrient application and tillage practices.

High transportation cost is a barrier which prevents land application of compost far away from where the compost is produced. As a result, use of compost in lawns is becoming a popular alternative in municipalities where compost is produced from municipal solid/biosolid waste. A four-year (2002 to 2005) field experiment was conducted on turfgrass [20% Kentucky Blue (Poa pratensis L.) + 80% Creeping Red Fescues (Festuca rubra L.)] grown on a Black Chernozem soil near Edmonton, Alberta, Canada, to determine the effect of rate and frequency of spring application of compost (prepared from soild/biosolid waste of city of Edmonton) on biomass, sward color, concentration and uptake of nutrients of sward, and soil chemical properties. There were three compost treatments: 50 Mg ha−1 annual; 100 Mg ha−1 (1st year) + 50 Mg ha−1 (2nd year) split, and 150 Mg ha−1 once in three years (2002, 2003 and 2004) applications. In addition, there were check (no fertilizers or compost) and annual nitrogen-phosphorus-potassium-su...

Over 14 million hectares of erosion prone cropland in the United States has been converted into grasslands through the Conservation Reserve Program (CRP) administered by the United States Department of Agriculture, however, studies of the effects of CRP enrollment on plant communities and subsequent plant succession are largely lacking. In Delta Junction, Alaska plant communities in CRP fields are transitioning from grasslands to shrub dominated plant communities, which are resulting in compliance problems with program regulations that state “fields must be maintained in a condition that permits easy conversion to cropland”. To determine plant succession and how previous land management and soils might influence the transition, we measured plant populations in 20 CRP fields throughout Delta Junction using modified-Whittaker plots. These data were combined with data on current management practices, previous farming history, soils, soil properties, diversity indices, and time since land was cleared and analyzed with nonmetric multidimensional scaling ordination to determine factors that influence plant succession. Time in the CRP was the only factor consistently influencing plant succession. As time in the CRP increased, the planted introduced grasses brome grass (Bromus inermis) and red fescue (Festuca rubra) and the native pteridophyte (Equisetum arvense) decreased, whereas a native grass (Calamigrostis canadensis), five native forb, two native shrub, and three native tree species increased. Plant diversity increased at a rate of more than 2 species per 1000 m2 per year. Regression analyses of plant species and plant groups using time in the CRP as the dependent variable resulted in the identification of outlier CRP fields with significantly more or less than expected covers of vegetation. All fields with these outliers had reasonable explanations for the differences in cover that were unrelated to the overall rate of plant succession. Current management practices will result in incompliant fields and different management practices that result in woody vegetation control is key to maintaining CRP fields in compliance.

The silk industry is important for south China's rural economy. Leaves of mulberry (Morus spp.) are used for silkworm production. Hubei province is one of the main silk-producing provinces in China. The objectives of this research were to survey the fertilization practices in the mulberry-producing regions in the province and to determine the best nutrition-management practice for mulberry plantations. A survey and a series of field experiments with N, P, K, and micronutrients were conducted from 2001 to 2002. In addition, a silkworm-growth experiment was also conducted by feeding leaves harvested from various fertilization treatments. The results indicate that poor soil fertility and unbalanced fertilization were the main factors limiting mulberry-leaf yield and quality in Hubei province. Nitrogen fertilization of mulberry has reached a high level (454kg ha -1 y -1 ) in Hubei province, but P- and K-fertilization rates have not been matched with N-fertilization rates as farmers are not aware of the significance of P and K. Balanced fertilization showed positive nutrient interactions with respect to mulberry yield and quality. Potassium application increased yield and quality (protein and sugar concentration) of mulberry leaves. Silkworm growth and cocoon quality were improved when silkworms were fed with the leaves derived from K-fertilized plants in comparison with those taken from control plots. Application of Mg, S, and B also significantly improved leaf sugar, essential and total amino acid concentrations, but did not increase leaf yield significantly. It is concluded that a fertilizer dose of 375 kg N ha -1 , 66kg P ha -1 , and 125kg K ha -1 is suitable for the cultivation of mulberry in the Hubei province along with Mg, S, and B, wherever necessary, for the improvement of yield and quality of mulberry leaves.