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This study investigated long-term fertilisation effects on soil microbiological characteristics of hydromorphic paddy soils. The study was conducted in 30-year-old experimental plots with various treatments involving chemical fertiliser (nitrogen, phosphorus, and potassium) alone or in combination with manure in relation to a control in a rice-rice-fallow system at the farm at Jiangxi Academy of Agricultural Science. The soil microbial biomass carbon (SMBC) and nitrogen (SMBN), microbial enzyme activity, and microbial community structure were analysed. Changes in levels of SMBC and SMBN in response to combinations of organic-inorganic fertilisers were significantly higher than for inorganic fertiliser treatment. Furthermore, activities of microbial enzymes (sucrase, urease, proteinase, acid phosphatase, and catalase) were significantly higher in combined than in inorganic fertiliser and control treatments. Additionally, the richness and evenness of soil bacteria were decreased by long-term fertilisation, especially inorganic, whereas the Shannon-Weiner and richness indexes of soil fungi were higher. Long-term fertilisation with high doses of combined organic-inorganic input significantly increased microbial biomass, enzyme activity, and fungal community diversity. However, the same input decreased bacterial community diversity. This study will be useful for improving fertilisation management in hydromorphic paddy soils. Additional keywords: chemical fertiliser; fertilisation; manure; microbiology. Received 22 May 2018, accepted 6 January 2019, published online 6 June 2019, Introduction Organic matter transformation represents one of the most important attributes for the management of soil fertility (Lalnunzira and Tripathi 2018), and is regulated by the activity of soil microorganisms [...]

To meet the global food demand in the coming decades, crop yields per unit area must increase. This can only be achieved by a further intensification of existing cropping systems and will require even higher inputs of N fertilisers, which may result in increased losses of nitrous oxide ([N.sub.2]O) from cropped soils. Enhanced efficiency fertilisers (EEFs) have been promoted as a potential strategy to mitigate [N.sub.2]O emissions and improve nitrogen use efficiency (NUE) in cereal cropping systems. However, only limited data are currently available on the use of different EEF products in sub-tropical cereal systems. A field experiment was conducted to investigate the effect of three different EEFs on [N.sub.2]O emissions, NUE and yield in a sub-tropical summer cereal cropping system in Australia. Over an entire year soil [N.sub.2]O fluxes were monitored continuously (3 h sampling frequency) with a fully-automated measuring system. The experimental site was fertilised with different nitrogen (N) fertilisers applied at 170 kg N [ha.sup.-1], namely conventional urea (Urea), urea with the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP), polymer-coated urea (PCU), and urea with the nitrification inhibitor nitrapyrin (Nitrapyrin). Nitrous oxide emissions were highly episodic and mainly controlled by heavy rainfall events within two months of planting and fertiliser N application. Annual [N.sub.2]O emissions in the four treatments amounted to 2.31, 0.40, 0.69 and 1.58 kg [N.sub.2]O-N [ha.sup.-1] [year.sup.-1] for Urea, DMPP, PCU and Nitrapyrin treatments, respectively, while unfertilised plots produced an average of 0.16 kg [N.sub.2]O-N [ha.sup.-1] [year.sup.-1]. Two of the tested products (DMPP and PCU) were found to be highly effective, decreasing annual [N.sub.2]O losses by 83% and 70%, respectively, but did not affect yield or NUE. This study shows that EEFs have a high potential to decrease [N.sub.2]O emissions from sub-tropical cereal cropping systems. More research is needed to assess if the increased costs of EEFs can be compensated by lower fertiliser application rates and/or yield increases., Introduction Nitrogen (N) fertiliser is a key input to achieve global food security and has made a crucial contribution to increasing food production over the past 50 years. Today the [...]

The world's coastal ecosystems are under stress. The numbers tell the story: Over 50 percent of the global population resides within 100 kilometers of a coastline, a thin ribbon of [...]

There is potential for using the Illinois soil nitrogen rest (ISNT) to improve N fertilizer recommendations for crops in the southeastern United States. The ISNT has been previously calibrated to predict N rates for corn (Zea mays L.) in North Carolina. This study evaluated the effects of sampling time, sampling depth, crop rotation, and fertilizer application on soil ISNT-N during a 2-yr period in the humid Coastal Plain and Piedmont regions of North Carolina. Ten sites were repeatedly sampled at 0- to 10-, 10- to 20-, and 20- to 30-cm depths in fall, mid-winter, and spring between October 2006 and May 2007. Illinois soil nitrogen test N, KCl-extractable soil N[O.sub.3]-N and N[H.sub.4]-N, and soil organic matter (SOM) derived by loss-on-ignition (LOI) were evaluated at each sampling. Temporal changes in these soil parameters were evaluated for various crop rotations and N fertilizer applications. Soil ISNT-N decreased with depth and showed significant variation with time at all three depths at all sites. Soil ISNT-N was influenced by crop rotation and tillage but was not significantly affected by N fertilizer applications. Considering all sites together, ISNT-N was well correlated with LOI; however, ISNT-N was not correlated with LOI across time within sites. This suggests that the ISNT measured a fraction of SOM that behaved somewhat independently with time. Abbreviations: ASN, amino sugar nitrogen; ISNT, Illinois soil nitrogen test; LOI, loss-on-ignition; SOM, soil organic matter. doi: 10.2136/sssaj2009.0253

Nitrogen and P leaching losses from fertilized turfgrass remain an environmental concern. In the present study, we examined the effects of sod type, fertilization, and irrigation on turf quality, N[O.sub.3]-N and P[O.sub.4]-P leaching following St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] sod installation. Treatments included muck- vs. sand-produced sod, no fertilization, fertilization with 4.9 g N [m.sup.-2] at installation or at 30 d after installation (DAI), and routine irrigation or irrigation at stress from 30 to 60 DAI. Drainage was collected from lysimeters installed in each plot and analyzed for N[O.sub.3]-N and P[O.sub.4]-P to determine total leaching Iosses. Across all treatments, drainage averaged 290, 902, and 604 mm during each of the three trials. Fertilization at 30 DAI significantly reduced P[O.sub.4]-P leaching losses compared to fertilization at 0 DAI. Muck sod type significantly reduced the quantity of N[O.sub.3]-N leached. Muck sod also significantly reduced P[O.sub.4]-P leached and resulted in better turf quality in two of the three trials. In the context of minimizing nutrient leaching, these results support the use of muck-grown sod established during low rainfall periods with fertilization delayed at least 30 DAI and with judicious use of irrigation. doi: 10.2135/cropsci2009.07.0411

Irrigated potato (Solanum tuberosum L.) production requires large inputs of N, and therefore has high potential for N loss including emissions of [N.sub.2]O. Two strategies for reducing N loss include split applications of conventional fertilizers, and single applications of polymer-coated urea (PCU), both of which aim to better match the timing of N availability with plant demand. The objective of this 3-yr study was to compare [N.sub.2]O emissions and potato yields following a conventional split application (CSA) using multiple additions of soluble fertilizers with single preplant applications of two different PCUs (PCU-1 and PCU-2) in a loamy sand in Minnesota. Each treatment received 270 kg of fertilizer N [ha.sup.-1] per season. An unfertilized control treatment was included in 2 of 3 yr. Tuber yields did not vary among fertilizer treatments, but [N.sub.2]O emissions were significantly higher with CSA than PCU-1. During 3 consecutive yr, mean growing season emissions were 1.36, 0.83, and 1.13 kg [N.sub.2]O-N [ha.sup.-1] with CSA, PCU-1, and PCU-2, respectively, compared with emissions of 0.79 and 0.42 kg [N.sub.2]O-N [ha.sup.-1] in the control. The PCU-1 released N more slowly during in situ incubation than PCU-2, although differences in [N.sub.2]O emitted by the two PCUs were not generally significant. Fertilizer-induced emissions were relatively low, ranging from 0.10 to 0.15% of applied N with PCU-1 up to 0.25 to 0.49% with CSA. These results show that N application strategies utilizing PCUs can maintain yields, reduce costs associated with split applications, and also reduce [N.sub.2]O emissions. Abbreviations: AN, ammonium nitrate; BMP, best management practice; CSA, conventional split application; PCU, polymer-coated urea. doi:10.2136/sssaj2009.0126

Nitrogen fertilization is essential for optimizing crop yields; however, it increases [N.sub.2]O emissions. The study objective was to compare [N.sub.2]O emissions resulting from application of commercially available enhanced-efficiency, N fertilizers with emissions from conventional dry granular urea in irrigated cropping systems. Nitrous oxide emissions were monitored from corn (Zea mays L.) based rotations receiving fertilizer rates of 246 kg N [ha.sup.-1] when in corn, 56 kg N [ha.sup.-1] when in dry bean (Phaseolus vulgaris L.), and 157 kg N [ha.sup.-1] when in barley (Hordeum vulgare L. ssp. vulgare). Cropping systems included conventional-till continuous corn (CT-CC), no-till continuous corn (NT-CC), no-till corn-dry bean (NT-CDb), and no-till corn-barley (NT-CB). In the NT-CC and CT-CC systems, a controlled-release, polymer-coated urea (ESN) and dry granular urea were compared. In the NT-CDb and NT-CB rotations, a stabilized urea source (SuperU) was compared with urea. Nitrous oxide fluxes were measured during two growing seasons using static, vented chambers and a gas chromatograph analyzer. Cumulative growing season [N.sub.2]O emissions from urea and ESN application were not different under CT-CC, but ESN reduced [N.sub.2]O emissions 49% compared with urea under NT-CC. Compared with urea, SuperU reduced [N.sub.2]O emissions by 27% in dry bean and 54% in corn in the NT-CDb rotation and by 19% in barley and 51% in corn in the NT-CB rotation. This work shows that the use of no-till and enhanced-efficiency N fertilizers can potentially reduce [N.sub.2]O emissions from irrigated systems. Abbreviations: CT, conventional-till; CT-CC, conventional-till continuous corn; DOY, day of the year; NT, no-till; NT-CC, no-till continuous corn; NT-CB, no-till corn--barley; NT-CDb, no-till corn--dry bean; WFPS, water-filled pore space. doi:10.2136/sssaj2009.0072

Alternative N fertilizers that stimulate low greenhouse gas emissions from soil are needed to reduce the impact of agriculture on global warming. Corn (Zea mays L.) grown in a calcareous silt loam soil in northwestern Italy was fertilized with a municipal solid waste compost and vetch (Vicia villosa Roth.) green manure. Their potential to reduce [N.sub.2]O and C[O.sub.2] emissions was compared with that of urea (130 kg N [ha.sup.-1]). Gaseous fluxes were measured for 2 yr in the spring (after soil incorporation of fertilizers) and in summer. In spring, the slow mineralization of compost reduced [N.sub.2]O emissions (0.11% of supplied N) relative to urea (3.4% of applied N), without an increase in C[O.sub.2] fluxes. Nitrous oxide (2.31% of fixed N) and C[O.sub.2] emissions from rapid vetch decomposition did not differ from urea. When [N.sub.2]O and C[O.sub.2] fluxes were combined, compost reduced by 49% the C[O.sub.2] equivalent emitted following urea application. Vetch did not show such an effect. In summer, no fertilizer effect was found on [N.sub.2]O and C[O.sub.2] emissions. Compost proved to be potentially suitable to reduce the C[O.sub.2] equivalent emitted after soil incorporation While vetch did not. For a thorough evaluation, net greenhouse gas emissions assessment should be extended to the entire N life cycle. Differences between calculated [N.sub.2]O emission factors and the default Tier 1 value of the Intergovernmental Panel on Climate Change (1%) confirmed the need for site- and fertilizer-specific estimations. Abbreviations: ADL, acid detergent lignin; [DELTA]C[O.sub.2]eq, increase in emitted C[O.sub.2] equivalent due to the applied fertilizer nitrogen with respect to the absence of fertilization; CK, check plots; COM, fertilization with compost; EF, nitrous oxide emission factor of fertilizer nitrogen applied; IPCC, Intergovermnental Panel or, Climate Change; LGM, fertilization with leguminous green manure; Ndfa, nitrogen derived from the atmosphere; PD, potential denitrification; PMN, potentially mineralizable nitrogen in anaerobiosis; SOC, soil organic carbon; SON, soil organic nitrogen; UR, fertilization with urea; WFPS, water-filled pore space. doi:10.2136/sssaj2009.0092

In tropical agroecosystems, limited N availability remains a major impediment to increasing yield. A [sup.15]N-recovery experiment was conducted in 13 diverse tropical agroecosystems. The objectives were to determine the total recovery of one single [sup.15]N application of inorganic or organic N during three to six growing seasons and to establish whether the losses of N are governed by universal principles. Between 7 and 58% (average of 21%) of crop N uptake during the first growing season was derived from fertilizer. On average, 79% of crop N was derived from the soil. When [sup.15]N-labeled residues were applied, in the first growing season 4% of crop N was derived from the residues. Average recoveries of [sup.15]N-labeled fertilizer and residue in crops after the first growing season were 33 and 7%, respectively. corresponding recoveries in the soil were 38 and 71%. An additional 6% of the fertilizer and 9.1% of the residue was recovered by crops during subsequent growing seasons. There were no significant differences in total [sup.15]N recovery, (average 54%) between N from fertilizer and N front residue. After five growing seasons, more residue N (40%) than fertilizer N (18%) was recovered in the soil, better sustaining the soil organic matter N content. Long-term total recoveries of [sup.15]N- labeled fertilizer or residue in the crop and soil were similar. Soil N remained the primary source of N for crops. As higher rainfall and temperature tend to cause higher [sup.15]N losses, management practices to improve N use efficiency and reduce losses in wet tropical regions will remain a challenge. Abbreviations: FUE, fertilizer use efficiency; NUE, nitrogen use efficiency; SOM, soil organic matter. doi:10.2136/sssaj2009.0192

The use of urea fertilizers in grasslands is likely to increase in areas with concentrated animal feeding operations as restrictions on manure applications are implemented. Concerns have been raised about the economic and environmental impacts of N[H.sub.3] loss from these urea fertilizers. This study evaluated N[H.sub.3] losses from Nitamin (a urea polymer), urea-N[H.sub.4]N[O.sub.3] (UAN), and granular urea applied to tall fescue (Festuca arundinacea Schreb.) plots at 50 kg N [ha.sup.-1] in fall and spring for 2 yr. Fertilizers were applied to circular plots (30-m diameter) and N[H.sub.3] loss was measured by the modified passive flux method for 69 to 120 d after application. In a separate laboratory study, Nitamin, UAN, and urea were surfaced applied to rescue thatch at 100 kg N [ha.sup.-1] and treatments were incubated at 24[degrees]C and 90% relative humidity for 31 d. In fall applications, urea lost more N[H.sub.3] (19% in 2004, 46% in 2005) than UAN or Nitamin, which were not different from each other (6% in 2004, 34% in 2005). In contrast, there were no differences among fertilizers in spring applications, with average losses of 13% in 2005 and 17% in 2006. In the laboratory study, urea lost significantly more N[H.sub.3] (24%) than UAN or Nitamin, which were not different from each other (average 9% loss). These results indicate that Nitamin and UAN undergo similar N[H.sub.3] losses, and that both fertilizers may lose less N[H.sub.3] than urea under conditions favorable to volatilization. Abbreviations: CRH, critical relative humidity; RH, relative humidity; UAN, urea--ammonium nitrate.

The mass consumption of agrochemicals, including manufactured fertilizers and pesticides, by industrialized agricultural systems worldwide threatens human health and the health of ecosystems. The production of these agricultural inputs is a highly energy- and capital-intensive process, and their application contributes to a variety of direct and indirect impacts on the environment. This study is an analysis of the relationships between international trade in agricultural products and the consumption of these synthetic compounds. Using OLS regression models and data from World Bank and UNFAO, we analyze cross-national data to examine the relationship between structural factors, such as economic development and export intensity, and both fertilizer and pesticide consumption. The findings are considered from the opposing theoretical perspectives of international political economy (IPE) and neo-liberal modernization (NLM). The results generally support the claims of IPE and contradict those of NLM, indicating that increases in exports of agricultural products contribute to increases in fertilizer and pesticide consumption within nations. These results call into question policies that promote increased trade liberalization in agricultural products.

The attribution of [N.sub.2]O emission factors to N inputs from chemical fertilizers requires an understanding of how those inputs affect the biological processes from which these emissions are generated. We propose a detailed model of soil N transformations as part of the ecosystem model ecosys for use in attributing [N.sub.2]O emission factors to fertilizer use. In this model, the key biological processes--mineralization, immobilization, nitrification, denitrification, root, and mycorrhizal uptake--controlling the generation of [N.sub.2]O were coupled with the key physical processes--convection, diffusion, volatilization, dissolution--controlling the transport of the gaseous reactants and products of these biological processes. Physical processes controlling gaseous transport and solubility caused large temporal variation in the generation and emission of [N.sub.2]O in the model. This variation limited the suitability of discontinuous surface flux chambers measurements used to test modeled [N.sub.2]O emissions. Continuous flux measurements using micrometeorological techniques were better suited to the temporal scales at which variation in [N.sub.2]O emission occurred and at which model testing needed to be conducted. In a temperate, humid climate, modeled [N.sub.2]O emissions rose nonlinearly with fertilizer application rate once this rate exceeded the crop and soil uptake capacities for added N. These capacities were partly determined by history of fertilizer use, so that the relationship between [N.sub.2]O emissions and current N inputs depended on earlier N inputs. A scheme is proposed in which [N.sub.2]O emission factors rise nonlinearly with fertilizer N inputs that exceed crop plus soil N uptake capacities.

Low growth rates of Pinus radiata D. Don plantations on soils of low nutrient status in Tasmania require the development of nutrient management systems involving fertilization throughout the life of the stand. Periodic fertilization through 15 yr, in a Pinus radiata D. Don plantation in northeastern Tasmania was evaluated for effects un stand growth and soil. Substantial stem volume increases due to N and P fertilizer, applied as ammonium sulfate and single superphosphate were observed. Two applications of P fertilizer totaling 144 kg P [ha.sup.-1] produced substantial increases in stem volume growth from 67 to 192 [m.sup.3] [ha.sup.-1]. With P plus 13 annual applications of N fertilizer at 100 kg N [ha.sup.-1][yr.sup.-1], stem volume growth increased from 192 to 344 [m.sup.3] [ha.sup.-1] over the 15-yr period. Although fertilizing every second and fourth year produced less response, these treatments had better fertilizer-use efficiency. Long-term fertilization resulted in increases in concentrations of nutrients in the forest floor and the surface soil. The highest rates of fertilization were accompanied by significant reductions in soil pH throughout the soil profile, from 4.1 to 3.4 units. Reduction in pH occurred with both nitrogenous and phosphatic fertilizers. Substantial reductions in exchangeable Mg concentrations, from 235 to 88 [micro]g[g.sup.-1], were also measured throughout the soil profile. The highest rate of N application significantly increased the total O2 horizon biomass, with N mass doubling within the O2 horizon.

We tested the hypothesis that particulate organic matter (POM) and aggregate dry mean weight diameter (DMWD) are related to fertilizer-use efficiency (FUE) and leaching susceptibility. Soil cores (15 cm diam. by 50 cm depth) were collected from 12 farm fields representing three cropping systems: conventional (CT) and no-tillage (NT) management of corn (Zea mays L.)-soybean [Glycine max (L.) Merr.] rotations, and CT applied to more diversified corn-soybean-based rotations (R-CT). Three of the four R-CT farms were organically managed. In a 95-d greenhouse trial, cores were seeded with corn, amended with [sup.15]N-labeled urea applied at four rates (0, 75, 150, 225 kg N [ha.sup.-1]), and subjected to a stressful moisture regime. Aggregate DMWD, which serves as a rough index of pore-size distribution, was greater in NT cores. Although total leached N was similar in all cropping systems, increased macropore flow in NT cores led to greater leaching of fertilizer N and less leaching of soil-derived N, as well as greater moisture stress and decreased plant N uptake. The R-CT cores had more POM and organic C in the top 30 cm of soil and higher crop biomass and biomass-N content. However, FUE in R-CT cores was relatively low since FUE does not account for contributions of indigenous N. For the same reason, FUE remained relatively high in CT systems despite less labile organic matter. Both FUE and SOM conservation declined with increasing N application rates. Increasing labile sources of N, reflected in POM pools, through crop diversification can substitute for incremental increases in fertilizer N and improve long-term productivity on Illinois Mollisols.

Fifteen years of N and P fertilizer addition to an Alaskan moist tundra increased aboveground biomass and primary production by 2.5 times. Species composition of the fertilized vegetation also changed dramatically, from a mix of graminoid, evergreen, deciduous, and moss species to strong dominance by a single, deciduous shrub species, Betula nana. Analysis of these simultaneous changes allows insights into the interactions between changes in resource availability and changes in species composition in regulating vegetation biomass, production, and element use. By the 15th year (1995), both new leaf production and total leaf mass were lower in fertilized than in control plots, although leaf area in fertilized plots was twice that of controls. This occurred because Betula produced thinner leaves than other species, with a high specific leaf area (SLA, leaf area per unit leaf mass). Woody stem mass also increased dramatically in fertilized plots, with secondary growth accounting for over half of aboveground net primary production, NPP. The large increase in wood production was made possible, in part, by the low cost of production of Betula's thin leaves, allowing greater allocation to secondary growth. Wood also had lower N concentrations than leaves, allowing large accumulations of wood at low N cost. Overall, aboveground N concentration in Betula did not change in fertilized relative to control plots, because its low-N wood mass increased more than its high-N leaf mass (with high SLA). Because Betula was so strongly dominant on the fertilized plots and was better able to dilute its greater N supply with new growth, community production and biomass in fertilized plots were higher, and N concentration was lower, than would have been the case if species composition had not changed. Aboveground biomass and leaf area of individual species and functional types were predicted accurately by regression against the number of hits per point-flame pin across the full range of data, including both treatments. Changes in overall canopy structure and leaf display due to fertilization were thus due mainly to changes in species composition, with no detectable effect of treatment on size/structure relationships within species or functional types. Key words: allocation; Arctic; biomass; Brooks Range, Alaska; fertilizer; nutrients; primary production; secondary growth; species composition; specific leaf area; tundra productivity.

Nutrient flows related to agricultural development in the Baltic States and Sweden after 1988 and the change from collective farms to a market economy with family farms are discussed. Changes in nitrogen and phosphorus flows in agriculture and into the Baltic Sea after independence from Russia came to the Baltic States are compared to changes in Sweden in the same time period.

A study of nonpoint source pollution of agricultural fertilizer in surface water was undertaken in the Iowa Loess Hills, using historical data and high frequency sampling to establish trends. Concentration of nitrate was found to increase from less than 1 mg/L in 1969 to over 20 mg/L in 1991, with 23% of the mean annual application of nitrogen estimated to remain stored or available for leaching or chemical conversion.

A characterization of the movement of an agricultural fertilizer from the surface to groundwater is undertaken and showed unsaturated zone groundwater system to have a high potential in storing unutilized nitrogen as nitrate. Loess hills were also shown to be the sensitive link in the agricultural landscape, which induces nitrate to leach into the groundwater. Time of sampling and landscape position were shown to affect measurements of concentration.

1 The rhizome growth patterns of the clonal plant Solidatto altissima were studied in response to mowing and fertilizer application in a field experiment. Rhizome systems of 120 clonal fragments were harvested in the spring of 1993, after 6 years of mowing (1987-92) and 2 years of fertilizer application (1991-92). The results were interpreted in the light of plant foraging theory. 2 The ages of the individual rhizomes comprising each rhizome system were determined and their length, number of offspring rhizomes, branching angles and the height of emerging shoots measured. Rhizomes were then washed, dried and weighed. 3 Persistent rhizomes, i.e. rhizomes that survived more than 1 year, were shorter and less numerous in mown plots and their dry mass was less than 50% of that in unmown plots. Thus, repeated mowing depleted the rhizomes of their stored resources and has been used as a measure to control the further spread of S. altissima. 4 In contrast, rhizomes established in 1992 produced 10% more daughter rhizomes, which were also 23% longer in mown than in unmown plots. 5 There was little evidence that the length, and no evidence that the number of rhizomes, was increased by fertilizer application. Nevertheless, fertilizer application increased the dry mass and decreased the specific length (length per unit dry mass) of rhizomes. 6 Rhizome branching angles were not consistently altered by the treatments. However, there was a significant interaction, i.e. angles increased in response to fertilizer in unmown but not in mown plots. 7 The observed rhizome growth patterns (3-5) could be explained by adaptive growth plasticity, i.e. foraging, in the first year followed by differential survival of long rhizomes in later years. However, the greater length of newly formed rhizomes in mown plots could also have been due to increased soil temperatures caused by the removal of standing biomass and litter, which increased irradiance at the soil surface. This suggests that the observed growth responses of the rhizome systems to mowing and fertilizer application were due to 'passive growth' rather than adaptive foraging. Keywords: clonal growth, plant foraging, plasticity, rhizome architecture

Many questions faced by forestry scientists are also faced by those concerned about basic ecology. Scientists have tried to develop ecosystem-based management approaches that maintain the complexity and function of a system. They often act in nontraditional roles at the biology/sociology/policy interface. In the US two approaches with very different goals and scientific priorities have emerged in forestry. In most industrial lands the emphasis is on greater productivity of wood fiber. Federal forest management focuses on protecting diversity and water. Long-term sustainability are important for any owner, private or public. Productive genotype selection, fertilization, harvesting practices that compact soil, pest problems related to intensive forestry and the potential of loss of species with no commercial value are issues to be faced. Biology, soils and hydrology are emphasized, but other aspects of forestry are reviewed.

Abstract The impact on ground water quality from increasing fertilizer application rates over the past 40 years is evaluated within a glacial aquifer system beneath a thick unsaturated zone. Ground [...]

For decades, farmers in Montana and the Dakotas have produced impressive yields of barley and wheat. But that bounty has come at a cost. Tilling the soil in the region's [...]

The use of an ammonia-based nitrogen fertilizer to soil may enhance biodegradation of the fumigant methyl bromide during the nitrification of bacteria. Specifically, the liming and application of the fertilizer and inoculation of the ammonia oxidation bacterium Nitrosomonas europaea can stimulate MeBr degradation in soil. As a consequence, the rate of MeBr flux into the atmosphere may be minimized following fumigation.

Subirrigated sands with surface-applied fertilizer bands are susceptible to considerable gravity-induced convection of fertilizer salts whenever the water table approaches within 30 to 45 cm of the soil surface and induces rapid fertilizer dissolution. Laboratory studies have been conducted on two sands from Manatee County in the vegetable and citrus production region along central Florida's Gulf Coast. Peak saturated-zone electrical conductivity (EC) values of 14 and 9 dS [m.sup.-1] were attained within 3 to 5 d at the 60-cm depth for columns of local sand having a water table maintained 2.5 and 22.5 cm below the soil surface, respectively. Such movement is far too rapid to be ascribed to reasonable diffusional or traditional convective-flow effects, and is instead attributed to gravity-induced convective flow, or fertilizer 'dropout'. Sectioned-column studies demonstrated near-surface EC values of 25 to 35 and 70 to 90 dS [m.sup.-1] for water tables maintained at the 15- and 45-cm depths, respectively. These same columns evidenced solute-pulse movement to the 8- to 10-cm depth and the 15- to 20-cm depth after 6 and 24 h, respectively, for water tables maintained at the 45-cm depth. Lower hydraulic conductivity, quite possibly as a result of increased soil organic matter content for these otherwise virtually identical fine sands, moderated such effects somewhat. Implications are discussed with respect to early-season fertilizer management in vegetable production regions of the southeastern Coastal Plain.

A high resolution global model of the terrestrial biosphere is developed to estimate changes in nitrous oxide ([N.sub.2]O) emissions from 1860-1990. The model is driven by four anthropogenic perturbations, including land use change and nitrogen inputs from fertilizer, livestock manure, and atmospheric deposition of fossil fuel N[O.sub.x]. Global soil nitrogen mineralization, volatilization, and leaching fluxes are estimated by the model and converted to [N.sub.2]O emissions based on broad assumptions about their associated [N.sub.2]O yields. From 1860-1990, global [N.sub.2]O emissions associated with soil nitrogen mineralization are estimated to have decreased slightly from 5.9 to 5.7 Tg N/yr, due mainly to land clearing, while [N.sub.2]O emissions associated with volatilization and leaching of excess mineral nitrogen are estimated to have increased sharply from 0.45 to 3.3 Tg N/yr, due to all four anthropogenic perturbations. Taking into account the impact of each perturbation on soil nitrogen mineralization and on volatilization and leaching of excess mineral nitrogen, global 1990 [N.sub.2]O emissions of 1.4, 0.7, 0.4 and 0.08 Tg N/yr are attributed to fertilizer, livestock manure, land clearing and atmospheric deposition of fossil fuel N[O.sub.x], respectively. Consideration of both the short and long-term fates of fertilizer nitrogen indicates that the [N.sub.2]O/fertilizer-N yield may be 2% or more.

DDT residues in soils undergoing long-term irrigation and superphosphate application trials were measured to determine the effects of agricultural practices on the levels of DDT and DDT residues in soil. Results show that irrigated soils had a total DDT residue level about 40% higher than unirrigated soils. Superphosphate-treated soils had lower levels of p,p'-DDT and total DDT residues compared to unfertilized soils. The results suggest that DDT and DDT residues tend to remain in soils for a long time.

A 24-year crop rotation study conducted on a medium textured Aridic Haploboroll in southwestern Saskatchewan, Canada, helped monitor soil organic matter in 0-to 0.15 and 0.15- to 0.3-m depths. The content of soil organic matter C and N was examined for the influence of cropping frequency, fertilization and crop variety. The variations in soil organic matter were linked to grain removal, NO3 leaching, crop residue and fertilizer inputs.

The utilization of fertilizer banding in Alaska is discussed. The response ofconventional seeded barley was compared to no-till-seeded barley. Different cold temperature fertilizer placement methods for barley were also evaluated. The reduction of seedling injury incidence from urea banded with the seed due to cold soils was also monitored. A delayed but increased emergence rate was derived as soil temperature was reduced by the placement of urea with the seeds.

The effects of soil acidity on rates of nitrogen release from various ureaform fractions are discussed. The cold water soluble, hot water soluble and the soluble in hotwater but not cold water fractions of a ureaform were analyzed of nitrogen content. Fitting linear increase and plateau models estimated the rate of nitrogen release. Adjustments in rates of applications were found to be necessary for the successful use of ureaform fertilizers.

SUMMARY (1) In the Vechtplassen area of The Netherlands, small fens are scattered in an agricultural landscape which is used for dairy production. Fens in groundwater discharge areas have been less affected by eutrophication than those in groundwater recharge area. (2) Hydrological and nutrient budgets (nitrogen, phosphorus, potassium) were measured in two fens from 1985 to 1987. (3) One fen, located in a groundwater recharge area, received polluted river water which compensated for evaporative and groundwater losses during the summer. This inflow, and precipitation, were the major inputs of water. Major hydrological outputs were evapotranspiration (summer) and subsurface outflow (winter). The second fen was located in a groundwater discharge area. It received river water only occasionally and the main hydrological inputs were groundwater discharge and precipitation. Evapotranspiration and subsurface outflow were the major hydrological outputs. (4) Although nutrient inputs, especially nitrogen, were enhanced as a result of agricultural activities, summer harvesting of above-ground vegetation resulted in a net loss of potassium and phosphorus from the fens. Nitrogen inputs almost equalled outputs. (5) Differences between the fens in their overall nutrient budgets were small. Annual differences in production of biomass and in nutrient uptake by the vegetation could not be explained by differences in the nutrient budgets. Primary production and nutrient uptake reflected differences in mineralization rates of nitrogen and phosphorus. The mineralization process is regulated by the amount of organic nutrient substrates which may be mineralized as well as by the substrate composition and the ionic composition of the fen water. (6) The young fens are primarily fed by external nutrient inputs and are characterized by nutrient accumulation in peat. In mature fens, the peat which has developed isolates the fen from its environs, and plant growth is driven by re-mineralization of nutrients that have accumulated in former periods. (7) Harvesting of vegetation effectively reduces phosphorus and potassium in the soil. Over the long term, a shift from nitrogen limitation towards phosphorus or potassium limitation is to be expected in the fens. However, regional land-use control is necessary to prevent a further increase in nutrient inputs.

The American Association of Plant Food Control Officials (AAPFCO) adopted standard language for Bulk Compost Rules and Regulations. It allows composters to reduce the risk to marketers of bulk compost when making nutrient claims.

Byline: M. Niamatullah, M. Khan, M. Q. Khan, M. Sadiq, K. U. Zaman, C.S. Hayat and S. Rehman ABSTRACT An experimental trial was carried out on two variable textured soils [...]

Byline: J.P. Painuly, S. Mahendra Dev This paper presents an overview of the environmental consequences of fertilizers and pesticides in agriculture and the measures needed to mitigate the adverse impact of these chemicals on environment. The issues are then analysed from the perspective of the use of fertilizers and pesticides in Indian agriculture. Fertilizer consumption in India is concentrated in about one-third of the cultivated area. Its use has been increasing but it is being used inefficiently. Pesticide use is also concentrated in five states and on a few crops such as rice, cotton and chillies. Evidence from micro studies on the environmental consequences of these chemicals is presented. It is suggested that the present methods of fertilizer and pesticide use and growth are not sustainable. There are several possible technologies and alternatives to reduce the adverse impact of these chemicals on the environment, such as biological control of pests, integrated pest management, development of pest-resistant varieties of crops, vermiculture. etc., that need to be supplemented through an economic approach. These issues need to be considered while formulating strategies for sustainable agriculture in India and other developing countries.

ABSTRACT: We investigated the effects of rain infiltration rate and manure application rate on the quality of leachate and runoff from four soils. Tall fescue (Festuca arundinacea Schreber) plots received [...]

Denitrification N losses from soils under no-tillage (NT) can reduce N-use efficiency and destroy the ozone layer if appreciable amounts of N oxides ([N.sub.2]O, NO) are lost. The objective of this study was to evaluate the effect of surface-applied urea rate (0, 70, and 210 kg N [ha.sup.-1]) and different application times [planting (PL) and six-leaf stage (V6)] on denitrification losses (DLs) in NT irrigated maize (Zea mays L.). The field experiment was carried out in the 1996 and the 1998 growing seasons, at Balcarce (37 [degrees] 45'S; 58 [degrees] 18'W), Argentina, on a Typic Argiudoll and a Petrocalcic Paleudoll. The annual mean rainfall in the area is 870 mm and annual mean temperature is 13.7 [degrees] C. Denitrification rates (DRs; [N.sub.2]O) were measured using [C.sub.2][H.sub.2] blockage core method. The DRs were highest between PL and the V6 because of higher water filled pore space (WFPS), and were closely associated with the WFPS ([r.sup.2] equal to 0.66 and 0.76 for 1996 and 1998, respectively). On average, accumulated DLs for the PL application were 7.6 and 9.8 kg [N.sub.2]O-N [ha.sup.-1] (5.5 and 2.6% of N applied for 70 and 210 kg N [ha.sup.-1], respectively). However, for application at the V6, accumulated DLs were 2.0 and 2.1 [N.sub.2]O-N kg [ha.sup.-1] (1.0 and 0.4% of N applied for 70 and 210 kg N [ha.sup.-1], respectively). The results indicate that for this soil and climatic zone, denitrification N losses were greater when the fertilizer was applied at PL than when fertilizer was applied at the V6.

Trading can be a cheaper answer to water quality problems, creating a win-win solution for all. Over the centuries, water has provided society with numerous products and services, including transport, [...]

Because native, shortgrass prairies are not typically fertilized and otherwise extensively managed, little information is available on their response to nitrogen (N) fertilization. An experiment was conducted in 1997 and 1998 to study the effects of N fertilization on forage yield and quality, forage height, and subsequent nitrate accumulation in the soil of a rangeland site consisting primarily of buffalograss [Buchloe dactyloides (Nutt.) Engelm.]. The N treatments were 0, 34, 68, 102, and 136 kg [ha.sup.-1] arranged in a Latin square design. An increase (P [is less than] 0.05) in forage dry matter (DM) yield was obtained with 34 kg [ha.sup.-1] N. Greater (P [is less than] 0.05) forage yields were achieved with an additional 102 kg [ha.sup.-1] N (total 136 kg [ha.sup.-1] N). Forage yields averaged 2540 kg [ha.sup.-1] in 1997 and 2340 kg [ha.sup.-1] in 1998. Nitrogen fertilization increased crude protein (CP) of buffalograss forage. Each unit of 34 kg [ha.sup.-1] N linearly increased CP up to approximately122 g [kg.sup.-1] of DM forage. Weather conditions influenced in vitro digestible dry matter (IVDDM). As long as moisture conditions were favorable for forage growth, IVDDM increased linearly with N fertilization rate. In 1997, IVDDM ranged from 565 g [kg.sup.-1] for the control to 658 g [kg.sup.-1] for the 102 kg [ha.sup.-1] N application rate. In 1998, IVDDM declined linearly (P [is less than] 0.05) with N fertilization rate. In vitro digestible dry matter averaged 539 g [kg.sup.-1] for the control to 482 g [kg.sup.-1] for the 136 kg [ha.sup.-1] N application rate. Nitrogen fertilization of buffalograss dominated semiarid rangeland can enhance forage production and quality. Nitrate accumulation in the soil was insignificant over the study period., A NUMBER OF FERTILIZATION TRIALS have been conducted on native and reseeded rangeland sites in the Great Plains (Huffine and Elder, 1960; Launchbaugh, 1962; Burzlaff et al., 1968; Warnes and [...]

Previous studies of pesticide fate in turfgrass have found less mobility and more rapid dissipation compared with studies using the same pesticide applied to bare soil. Few direct comparisons of pesticide mobility and dissipation in turfgrass vs. bare soil have been conducted. The mobility mad persistence of cyproconazole [Alpha]-(4-chlorophenyl) -[Alpha]-(1-cyclopropylethyl)-1H-1,2,4-triazole-1-ethanol] on bare soil (Flanagan silt loam; fine, smectitic, mesic Aquertic, Argiudoll) and turf containing varying levels of organic matter was examined under field conditions. Twenty-centimeter-diameter polyvinyl chloride (PVC) cylinders were installed in either creeping bentgrass turf (Agrostis palustris Huds.), or in turf in where either 33, 67, or 100% of the thatch and plant material had been removed, Cyproconazole was applied at 403 g a.i. [ha.sup.-1] on 15 July 1996 and 8 July 1997. Replicate sampling cylinders were removed 2 h after treatment (HAT) and 4, 8, 16, 32, 64, and 128 d after treatment (DAT). Cylinder cores were sectioned into depths and assayed for cyproconazole by gas chromatography. On all sampling days, increasing the amount of surface organic matter decreased the amount of cyproconazole in the 0- to 1-, 1- to 3-, 3- to 5-, and 5- to 15-cm core sections. The amount of cyproconazole detected in the soil under a full stand of turf at 4 and 32 DAT was 1 and 11%, respectively, of that detected in bare soil. Cyproconazole residues never exceeded 20 µg [kg.sup.-1] in the 15- to 30-cm core section of any treatment. The half-life of cyproconazole decreased from 129 d in bare soil to 12 d in a full bentgrass turf. Cyproconazole movement below 5 cm in the soil was reduced with increasing amounts of turfgrass thatch, and as little as one-third of a full stand of turf greatly decreased the half-life of cyproconazole. Application of cyproconazole to turfgrass results in less mobility and more rapid dissipation than is typically reported in other agronomic crops., THERE ARE MANY ADVANTAGES to the environment of maintaining a stand of turfgrass (Beard, 1994), but serious questions have been posed in recent years concerning the use of synthetic fertilizers [...]

Angus x Hereford heifers (n = 50) were randomly assigned to bahiagrass pastures treated with biosolids varying in mineral content and evaluated for mineral status, with special attention to Cu. Biosolids and [NH.sub.4][NO.sub.3] were all applied at the rate of either 179 kg N/ha (X) or twice this (2X). Fertilizer was applied to .81-ha pastures for the following treatments: 1) Baltimore biosolids (1X = 179 kg N/ha); 2) Baltimore biosolids (2X = 358 kg N/ha); 3) Tampa biosolids (1X = 179 kg N/ha); 4) Tampa biosolids (2X = 358 kg N/ha); or 5) control [NH.sub.4][NO.sub.3] (1X = 179 kg N/ha) applied at two times. Pastures were divided into five blocks with each treatment represented once in each block. Copper loads varied from 8.8 to 42.2 kg/ha, and Mo loads varied from .27 to 1.11 kg/ha. Heifers (two per pasture) grazed their assigned pastures exclusively for 176 d. Liver biopsies were taken from all animals at d 1, 99, and 176, and blood samples on d 1, 50, 99, 135, and 176. Liver and plasma were analyzed for selected mineral contents, and blood was analyzed for hemoglobin and hematocrit. Experimental animals were generally low in mineral status when assigned to pastures and deficient in Se and P. By d 50, plasma Ca, Mg, Se, P, and Zn were adequate for all treatments. Plasma Cu declined (P [is less than] .03) for all treatments from d 50 to 176. Plasma Cu reflected depleted liver Cu storage, with the two Tampa and highest Baltimore treatment means lower in plasma Cu than the control at 176 d. Liver Fe concentrations were adequate for all treatments, and Mo concentrations ([is less than] 2.18 mg/kg) did not approach levels indicative of toxicity. Liver Cu declined (P [is less than] .05) with time for all treatments. By d 99, animals receiving the two Baltimore treatments and the lowest Tampa application rate had lower (P [is less than] .05) liver Cu than the control, and all treatments were lower at 176 d. The decline of animal Cu status (liver and plasma) reflects the low Cu status of bahiagrass and the possibility of high forage S (.30 to .47%) interfering with Cu metabolism. Forage Mo was low but was slightly higher in biosolids-treated pastures. High levels of biosolids applications to bahiagrass pastures were not detrimental to mineral status except Cu, which had a tendency to decline in plasma and for all biosolids treatments declined in liver. Key Words: Biosolids, Cattle, Fertilizers, Minerals, Pastures

Many studies have demonstrated ineffectiveness of finely ground phosphate rock (PR) use due to the low solubility of its P contents. This study was conducted to develop a simple, effective, and environmentally sound process to improve P availability of PR to crops by using a phosphate-solubilizing fungus (PSF), Aspergillus niger BCC F.194, isolated from tropical acid soils. The optimum incubation period and the optimum level of PR were determined. The P-solubilizing effect of the supernatant of 9-d-old liquid culture supernatant (LCS) of the fungus was also determined by reacting it at various concentrations with Morrocan phosphate rock (MPR). The inoculation of the growth media with the PSF A. niger resulted in the highest P solubility of the rock after 9 d of culturing at 2.5 g [L.sup.-1] MPR. Up to a certain degree, direct inoculation of fungal biomass and its LCS onto MPR caused a remarkable increase in 2% citric acid-soluble P, but not in water-soluble P content. The possibilities of using the LCS instead of [H.sub.2][SO.sub.4] in superphosphate (SP) production and using both with lower [H.sub.3][PO.sub.4] concentrations were investigated with MPR as raw materials. Replacement of [H.sub.2][SO.sub.4] by the LCS in the SP production process yielded a comparable 2% citric acid-soluble P content. Combining the LCS and [H.sub.2][SO.sub.4] reduced the consumption of [H.sub.3][PO.sub.4] that occurs in standard SP production. This LCS technique provides a practical means for an effective bioactivation of PR intended for both as a P fertilizer and a raw material of the SP.

Human activity, such as agricultural fertilizer use, has increased the amount of nitrogen deposited onto forests from the atmosphere. The photosynthetic response to this in evergreen needleleaf forests has been [...]

POTOMAC, MARYLAND--To get a handle on one of the world's biggest environmental headaches, think about dinner. Say that tonight you eat 100-gram helpings of both rice and chicken. Producing those [...]

Perchlorate concentrations in common garden fertilizers have been found to range from 0.15% to 0.84% by weight, but the fertilizer industry strongly disputes this finding. Perchlorate, which is not currently regulated, has been found to affect the thyroid and the production of thyroid hormones. The EPA recommends that drinking water have perchlorate limits ranging from 4 to 18 ppb.

Issues discussed concern the use of potentially harmful substances in the production of fertilizers due to a loophole in the Resource Conservation and Recovery Act which allows the transfer of industrial waste to fertilizer companies. Proposed studies on the effects of these chemicals in the soil are detailed.

Industrial power plants take most of the flack for climate change. But nature's plants are not blameless: agricultural land is responsible for about 14% of the world's greenhouse-gas emissions, slightly [...]