For many years, crop potassium (K) availability has been estimated by soil testing the plow layer for exchangeable K, in conjunction with potassium chloride fertilization widely promoted as an essential prerequisite for ensuring crop yield and quality. As rigorously documented in our paper, both components of chemical-based K management are seriously flawed by the lack of a scientific basis. Under the pretext of providing economic benefit for the producer and a healthy food supply for the public at large, the real purpose is to generate revenue for the fertilizer industry.

The objectives of a solute transport study determine the form of the subsequent modeling and experimental efforts. In addition, to achieve the study objectives, it is essential that the modeling approach and experimental design are consistent with each other. For example, the efficacy of model discrimination and parameter estimation strategies is strongly contingent on experimental design. Likewise, development of an effective experimental design is generally best achieved on the basis of hypothesis testing regarding specific candidate transport descriptions. The connection between experimental design and parameter estimation is illustrated using sensitivities, which are variations in predicted solute concentrations resulting from variations in model parameters. These sensitivities can be used to develop robust experimental designs with respect to parameter estimation. Criteria for model discrimination are presented. Finally, field studies of the spatial structure of transport variabilities are reviewed and the role of variability structure in determining the appropriate scale for a transport description is discussed. The influence of measurement scale on model discrimination and parameter estimation is examined using data from recent field studies. These examples illustrate that an understanding of the structure of variabilities can greatly reduce sample requirements and enhance process identification and model calibration efforts. Possible areas of future research also are discussed.

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Effects of sub-millimeter scale heterogeneity in chemical and microbial distributions on atrazine degradation were examined using Pseudomonas sp. strain ADP introduced into soil at a population mimicking atrazine-adapted soils (~2000 cells/g), and employing a range of soil water pressures (?100, ?300, ?500 kPa). Heterogeneous cell distribution was employed in all treatments whereas uniformity of distribution was a variable for atrazine introduction. Two methods of initially distributing atrazine in soil were examined. Proximally-applied atrazine (PAA) was intended to yield elevated atrazine concentrations in the vicinity of the degraders. Dispersed atrazine (DA) was introduced to distribute the chemical uniformly as compared to the distribution of degraders. Both rate and extent of degradation were greater than PAA, regardless of water content, presumably due to proximity of atrazine to degraders. Biodegradation decreased with decreasing water content for both application methods, attributed to decreases in atrazine’s effective diffusion. Mineralization of nearly 100% of DA in soils receiving a heterogeneous inoculum with a greater cell density (~107 cells/g) indicates that biodegradation was limited by the distance atrazine had to diffuse. Results support the hypothesis that enhanced populations of atrazine degraders, as reported elsewhere for atrazine-adapted soils, though heterogeneously distributed, may overcome bioavailability limitations.

There are increasingly important challenges associated with assessing the potential non-point source (NPS) pollution hazards which result from regionalscale agricultural activities. The increasing availability of geographic information system (GIS) technology to those involved in assisting with land-use decisions has resulted in the proliferation of multicolored maps for many environmentally sensitive issues. How useful are these maps to those in the decision-management arena? The focus of this chapter, relative to assessing NPS pollution in a GIS framework, is what the status and shortfalls of regional-scale NPS vulnerability assessments are and what still needs to be done to make them more useful in the decision-management arena.

Intensive fertilizer usage of KCl has been inculcated as a prerequisite for maximizing crop yield and quality, and relies on a soil test for exchangeable K in the plow layer to ensure that soil productivity will not be limited by nutrient depletion. The interpretive value of this soil test was rigorously evaluated by: (1) field sampling to quantify biweekly changes and seasonal trends, (2) characterizing the variability induced by air drying and the dynamic nature of soil K reserves and (3) calculating the K balance in numerous cropping experiments. These evaluations leave no alternative but to question the practical utility of soil K testing because test values cannot account for the highly dynamic interchange between exchangeable and non-exchangeable K, exhibit serious temporal instability with or without air drying and do not differentiate soil K buildup from depletion. The need for routine K fertilization should also be questioned, considering the magnitude and inorganic occurrence of profile reserves, the recycling of K in crop residues and the preferential nature of K uptake. An extensive survey of more than 2100 yield response trials confirmed that KCl fertilization is unlikely to increase crop yield. Contrary to the inculcated perception of KCl as a qualitative commodity, more than 1400 field trials predominately documented a detrimental effect of this fertilizer on the quality of major food, feed and fiber crops, with serious implications for soil productivity and human health.

Journal of Environmental QualityVolume 39, Issue 2 p. 753-756 Letter to the Editor Reply to Comments on "Synthetic Nitrogen Fertilizers Deplete Soil Nitrogen: A Global Dilemma for Sustainable Cereal Production," by R.L. Mulvaney, S.A. Khan, and T.R. Ellsworth in the Journal of Environmental Quality 2009 38: 2295–2314 R. L. Mulvaney, Corresponding Author R. L. Mulvaney lesssoiln@gmail.com Department of Natural Resources and Environmental Sciences, Turner Hall, 1102 S. Goodwin Ave., University of Illinois, Urbana, IL, 61801lesssoiln@gmail.comSearch for more papers by this authorS. A. Khan, S. A. Khan Department of Natural Resources and Environmental Sciences, Turner Hall, 1102 S. Goodwin Ave., University of Illinois, Urbana, IL, 61801Search for more papers by this authorT. R. Ellsworth, T. R. Ellsworth Department of Natural Resources and Environmental Sciences, Turner Hall, 1102 S. Goodwin Ave., University of Illinois, Urbana, IL, 61801Search for more papers by this author R. L. Mulvaney, Corresponding Author R. L. Mulvaney lesssoiln@gmail.com Department of Natural Resources and Environmental Sciences, Turner Hall, 1102 S. Goodwin Ave., University of Illinois, Urbana, IL, 61801lesssoiln@gmail.comSearch for more papers by this authorS. A. Khan, S. A. Khan Department of Natural Resources and Environmental Sciences, Turner Hall, 1102 S. Goodwin Ave., University of Illinois, Urbana, IL, 61801Search for more papers by this authorT. R. Ellsworth, T. R. Ellsworth Department of Natural Resources and Environmental Sciences, Turner Hall, 1102 S. Goodwin Ave., University of Illinois, Urbana, IL, 61801Search for more papers by this author First published: 01 March 2010 https://doi.org/10.2134/jeq2010.0002leCitations: 6 All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume39, Issue2March 2010Pages 753-756 RelatedInformation

Cereal production that now sustains a world population of more than 6.5 billion has tripled during the past 40 yr, concurrent with an increase from 12 to 104 Tg yr(-1) of synthetic N applied largely in ammoniacal fertilizers. These fertilizers have been managed as a cost-effective form of insurance against low yields, without regard to the inherent effect of mineral N in promoting microbial C utilization. Such an effect is consistent with a net loss of soil organic C recently observed for the Morrow Plots, America's oldest experiment field, after 40 to 50 yr of synthetic N fertilization that substantially exceeded grain N removal. A similar decline in total soil N is reported herein for the same site and would be expected from the predominantly organic occurrence of soil N. This decline is in agreement with numerous long-term baseline data sets from chemical-based cropping systems involving a wide variety of soils, geographic regions, and tillage practices. The loss of organic N decreases soil productivity and the agronomic efficiency (kg grain kg(-1) N) of fertilizer N and has been implicated in widespread reports of yield stagnation or even decline for grain production in Asia. A major global evaluation of current cereal production systems should be undertaken, with a view toward using scientific and technological advances to increase input efficiencies. As one aspect of this strategy, the input of ammoniacal N should be more accurately matched to crop N requirement. Long-term sustainability may require agricultural diversification involving a gradual transition from intensive synthetic N inputs to legume-based crop rotations.

Variable-rate nutrient management relies on soil fertility maps, yet the associated uncertainty is typically ignored in developing recommendations. In this article, ordinary kriging (OK) and several alternatives that rely on local estimates of uncertainty derived via probability kriging (PK) are evaluated for developing phosphorus (P) and potassium (K) fertilizer recommendations, using soil data collected at two different intensities. A decision support framework that incorporates economic and agronomic criteria to derive block-average optimal quantile estimates (Opt Q) maximized net return for an 8-year fertilization program. The economic results show an increase of $7.31 ha(-1) and $1.04 ha(-1) for P and K fertilization, respectively, using Opt Q rather than OK with the 0.2-ha sampling grid and $14.79 ha(-1) and $8.93 ha(-1) for P and K fertilization, respectively, using the 0.5-ha sampling grid. These results illustrate the importance of accounting for estimation uncertainty in developing variable-rate fertilizer recommendations.

Intensive use of N fertilizers in modern agriculture is motivated by the economic value of high grain yields and is generally perceived to sequester soil organic C by increasing the input of crop residues. This perception is at odds with a century of soil organic C data reported herein for the Morrow Plots, the world's oldest experimental site under continuous corn (Zea mays L.). After 40 to 50 yr of synthetic fertilization that exceeded grain N removal by 60 to 190%, a net decline occurred in soil C despite increasingly massive residue C incorporation, the decline being more extensive for a corn-soybean (Glycine max L. Merr.) or corn-oats (Avena sativa L.)-hay rotation than for continuous corn and of greater intensity for the profile (0-46 cm) than the surface soil. These findings implicate fertilizer N in promoting the decomposition of crop residues and soil organic matter and are consistent with data from numerous cropping experiments involving synthetic N fertilization in the USA Corn Belt and elsewhere, although not with the interpretation usually provided. There are important implications for soil C sequestration because the yield-based input of fertilizer N has commonly exceeded grain N removal for corn production on fertile soils since the 1960s. To mitigate the ongoing consequences of soil deterioration, atmospheric CO(2) enrichment, and NO(3)(-) pollution of ground and surface waters, N fertilization should be managed by site-specific assessment of soil N availability. Current fertilizer N management practices, if combined with corn stover removal for bioenergy production, exacerbate soil C loss.

Soil Science Society of America JournalVolume 71, Issue 1 p. 254-254 Comment & Letter to the Editor Comments on “Need for a Soil-based Approach in Managing Nitrogen Fertilizers for Profitable Corn Production” and “Soil Organic Nitrogen Enrichment Following Soybean in an Iowa Corn-Soybean Rotation” Laurence Greenfield, Corresponding Author Laurence Greenfield [email protected] School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch, New ZealandCorresponding author ([email protected]).Search for more papers by this author Laurence Greenfield, Corresponding Author Laurence Greenfield [email protected] School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch, New ZealandCorresponding author ([email protected]).Search for more papers by this author First published: 01 January 2007 https://doi.org/10.2136/sssaj2006.0286lCitations: 1Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat No abstract is available for this article. References 1Bremner, J.M. Organic nitrogen in soils. p. 93–132. W.V. Bartholomew, and F.E. Clark (ed.) Soil nitrogen. Agron. Monogr. 10. ASA, Madison, WI. 1965 2Foster, A.B. Chitin. Adv. Carbohydrate Chem. 1960 15 371–393 3Greenfield, L.G. The origin and nature of organic nitrogen in soil as assessed by acidic and alkaline hydrolysis. Eur. J. Soil Sci. 2001 52 575–583. https://doi.org/10.1046/j.1365-2389.2001.00419.x, http://gateway.isiknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=agrocropsoil&KeyUT=000173050300004&DestLinkType=FullRecord&DestApp=WOS_CPL&UsrCustomerID=523bbf5d2a868de7bbaeea0bc70ec0e4 4Khan, S.A. A simple soil test for detecting sites that are nonresponsive to nitrogen fertilization. p. 29–46. R.G. Hoeft (ed.) Illinois Fertilizer Conference 2001. Proc. Coop. Ext. Serv., Univ. of Illinois, Urbana-Champaign. 2001 5Martens, D.A. Soil amino acid composition quantified by acid hydrolysis and anion chromatography-pulsed amperometry. J. Agric. Food Chem. 2003 51 6521–6529. https://doi.org/10.1021/jf034422e, http://gateway.isiknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=agrocropsoil&KeyUT=000185990500025&DestLinkType=FullRecord&DestApp=WOS_CPL&UsrCustomerID=523bbf5d2a868de7bbaeea0bc70ec0e4 6Martens, D.A. Soil organic nitrogen enrichment following soybean in an Iowan corn-soybean rotation. Soil Sci. Soc. Am. J. 2006 70 382–392. https://doi.org/10.2136/sssaj2005.0112, http://gateway.isiknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=agrocropsoil&KeyUT=000236009100008&DestLinkType=FullRecord&DestApp=WOS_CPL&UsrCustomerID=523bbf5d2a868de7bbaeea0bc70ec0e4 7Mulvaney, R.L. A soil organic nitrogen fraction that reduces the need for nitrogen fertilization. Soil Sci. Soc. Am. J. 2001 65 1164–1172. https://doi.org/10.2136/sssaj2001.6541164x, http://gateway.isiknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=agrocropsoil&KeyUT=000172918400018&DestLinkType=FullRecord&DestApp=WOS_CPL&UsrCustomerID=523bbf5d2a868de7bbaeea0bc70ec0e4 8Mulvaney, R.L. Need for a soil-based approach in managing nitrogen fertilizers for profitable corn production. Soil Sci. Soc. Am. J. 2006 70 172–182. https://doi.org/10.2136/sssaj2005.0034, http://gateway.isiknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=agrocropsoil&KeyUT=000235088200020&DestLinkType=FullRecord&DestApp=WOS_CPL&UsrCustomerID=523bbf5d2a868de7bbaeea0bc70ec0e4 9Stevenson, F.J. Organic forms of soil nitrogen. p. 67–114. F.J. Stevenson (ed.) Nitrogen in agricultural soils. Agron. Monogr. 22. ASA and SSSA, Madison, WI. 1982 Citing Literature Volume71, Issue1January 2007Pages 254-254 ReferencesRelatedInformation

Nitrogen fertilization for corn (Zea mays L.) production has relied extensively on yield‐based recommendations that were developed to represent regional averages, yet are routinely applied to individual fields, on the assumption that fertilizer N serves as the major supply for crop N uptake. Using data from 102 on‐farm N‐response studies, an evaluation was conducted of the Illinois proven‐yield (PY) method for accuracy and economic profitability on a site‐by‐site basis. As additional objectives, the Illinois soil N test (ISNT) was evaluated for detecting whether N fertilization was economical, and for quantifying crop response to N fertilization relative to soil and management factors. For 18% of the site‐years studied, N recommendations by the PY method were accurate to within 20 kg ha−1, whereas 13% were underfertilized by 25 to 129 kg ha−1 (60 kg ha−1 on average) at a current cost of $5 to $170 ha−1 ($75 ha−1 on average), and 69% were overfertilized by 21 to 235 kg ha−1 (103 kg ha−1 on average) at a cost of $12 to $130 ha−1 ($57 ha−1 on average). The latter group included 30 site‐years that were completely nonresponsive to N fertilization, all but two of which were predicted by site‐average ISNT values assuming a critical test level of 230 mg kg−1 This level was exceeded for 19 of 69 responsive site‐years, mostly during 2001–2003 when corn followed soybean (Glycine max L. Merr.) with high plant populations. A higher critical test level would have been required under such conditions, owing to more extensive residue inputs that would promote microbial N immobilization, and increased crop uptake of mineralized soil N. The ISNT was significantly related to crop N requirement, and was the most powerful predictor of error in PY recommendations (P < 0.001).

We observed a group of 18 wood bison, of mixed sex and age classes, swimming across a 1.7 km wide section of the Liard River on 16 July 2002. Water levels and flow rates were above the long-term average for that time of year, and there was a river current of 14-16 km/h. The animals took at least 27 minutes to negotiate their 3.6 km swim. Younger animals were able to keep more of their head and body above the water level than older mature males. Calves of the year, observed swimming across a secondary channel of the river on 15 July 2003, had only their heads above water. Bison are capable of swimming across lakes and rivers (Wood Buffalo National Park, Yellowstone National Park), but well-documented cases of bison navigating rapidly flowing northern rivers are rare. Open-water crossings of the Liard River are important to the ecology of the Nahanni wood bison population, especially since seismic activity in the Liard River Valley is likely to increase.

A systematic analysis of the effect of displacement length, soil texture, and steady state water flux (q) on solute transport was performed on saturated repacked loam and sandy loam soil columns to identify the simplest possible description that was consistent with the observations across all of the breakthrough curves (BTCs) for each data set. All 39 BTCs obtained from loam and 21 from sandy loam soils, with column lengths of 10, 20, and 30 cm, and a two‐order magnitude variation in measured pore water velocity (vm), were fitted simultaneously and global estimates of parameters [dispersivity (λ) and molecular diffusion coefficient (D0)] were obtained. We showed that a two‐parameter global dispersion relationship (D = λvm + D0, where D is the apparent diffusion coefficient) accurately represents the spreading process for all 39 loam soil BTCs (r2 > 0.99), whereas a single global parameter (D = λvm) was all that was required for the sandy soil (r2 > 0.98). The globally fitted λ was independent of displacement length and vm D remained independent of vm in the lower velocity ranges; however, a linear relationship between vm and fitted D was obtained for vm > 0.1 cm h−1 The results of this study illustrated the importance of molecular diffusion. In addition, we identified a nonlinear relationship between vm and average solute velocity (vs), which suggested that the anion exclusion volume decreased with increasing vm

The Hook Lake Wood Bison Recovery Project (HLWBRP) is a wildlife conservation project aimed at recovering a captive, disease-free herd of wood bison (Bison bison athabascae) from a wild herd infected with bovine tuberculosis (Mycobacterium bovis) and brucellosis (Brucella abortus). The disease eradication protocol that we have used involves a combination of techniques, including (1) orphaning of newborn wild-caught calves to minimize exposure to B. abortus and M. bovis, (2) testing calves for maternal antibodies to brucellosis in the field prior to inclusion in the project, (3) isolating calves in pairs to prevent potential spread of disease, (4) prophylactic treatment using antimycobacterial and anti-Brucella drugs, and (5) an intensive whole-herd testing program for both diseases and removal of reactors. From 1996 to 1998, we captured a total of 62 calves; presently, 58 individuals comprise the founder herd. The captive-born cohorts consist of 7 two-year-olds, 21 yearlings, and 22 calves. To date, there have been no cases of bovine tuberculosis or brucellosis in the captive herd.

Anthrax outbreaks in northern Canada have implications for ongoing recovery efforts for the threatened wood bison and may pose a health risk to humans, other wildlife, and domestic livestock. RWED and WBNP maintain Anthrax Emergency Response Plans (AERPs) for their respective jurisdictions. An AERP is a pre-planned logistical framework for responding effectively and rapidly to an outbreak so as to minimize spread of the disease, reduce environmental load of spores available for future outbreaks, and minimize risk to public health. In this paper, we describe the main components of an AERP and outline areas for future research.