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With the advent of well‐fertilized corn (Zea mays L.) raonocultures with large amounts of residues returned to the soil, the question arose as to whether organic matter could be maintained at satisfactory levels in Corn Belt soils. To answer this question changes in the amounts and composition of the soil organic matter were determined in a field experiment where different types [alfalfa (Medicago sativa L.), cornstalks, sawdust, oat straw (Avena sativa L.), and bromegras(Bromus inermis Leyss)] and amounts (from 0 to 16 tons/ha/yr) plant residues were added to Marshall silty clay loam (Typic Hapludoll) for 11 consecutive years. The soil was cropped to corn and large amounts of N fertilizer were added. Organic C, N, S, and P contents of the soils increased in proportion to the amount of plant residues added. After 11 years contents of the 0‐ to 15‐cm depth of the check plots were 1.6% C, 0.15% N, 0.023% S, and 0.018% P. Average increases over the check for C, N, S, and P were 47, 37, 45, and 14%, respectively, for the 16‐ tons/ha/yr treatment. Type of plant residue when added at 8 tons/ha/yr did not influence the C or P contents of the soils differently. The organic N and S contents, however, were lower with sawdust than with the other residues. Cumulative effects of increasing quantities of organic residues on available nutrients in the soils showed that NH4‐N production, weak‐acid‐soluble P, and exchangeable K increased significantly. The amount of cornstalk residue needed to prevent loss of organic C was estimated to be 6 t/ha/yr.

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NCSOIL is a submodel of a larger program NTRM (nitrogen‐tillage‐residue management). NCSOIL computes short‐term dynamics of carbon and nitrogen organics, ammonium, and nitrate which result from the processes of residue decomposition, mineralization, immobilization, nitrification, and denitrification. Both total and isotopic nitrogen are considered. NCSOIL is built on the concept of catenary sequence of heterogenous substrates. The active soil organic phase is divided in two pools which are dynamic, defined by their kinetic rate constants and their position in the model structure. Residues are defined in terms of their chemical or morphological nature. A double feedback loop in the carbon flow adjusts the rate of residue decomposition and the efficiency factor to the availability of inorganic nitrogen. NCSOIL was calibrated with, and its behavior contrasted against published and unpublished data from an experiment reported by Chichester et al. in Soil Science (see p. 455, vol. 120): “Relative Mineralization Rates of Indigenous and Recently Incorporated 15‐N labeled Nitrogen.” Experimental results of the Chichester et al. experiment were discussed in view of computer‐simulated flow rates and substrate concentrations.

On 27 August 2013, during the Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys field mission, NASA's ER‐2 research aircraft encountered a region of enhanced water vapor, extending over a depth of approximately 2 km and a minimum areal extent of 20,000 km2 in the stratosphere (375 K to 415 K potential temperature), south of the Great Lakes (42°N, 90°W). Water vapor mixing ratios in this plume, measured by the Harvard Water Vapor instrument, constitute the highest values recorded in situ at these potential temperatures and latitudes. An analysis of geostationary satellite imagery in combination with trajectory calculations links this water vapor enhancement to its source, a deep tropopause‐penetrating convective storm system that developed over Minnesota 20 h prior to the aircraft plume encounter. High resolution, ground‐based radar data reveal that this system was composed of multiple individual storms, each with convective turrets that extended to a maximum of ~4 km above the tropopause level for several hours. In situ water vapor data show that this storm system irreversibly delivered between 6.6 kt and 13.5 kt of water to the stratosphere. This constitutes a 20–25% increase in water vapor abundance in a column extending from 115 hP to 70 hPa over the plume area. Both in situ and satellite climatologies show a high frequency of localized water vapor enhancements over the central U.S. in summer, suggesting that deep convection can contribute to the stratospheric water budget over this region and season.

A T times during the course of research that has never been far removed from the humic sciences, authors have experienced frustration, but more often they have experienced excitement and anticipation, sensations that cause scientists to "scorn delights and live laborious days". Frustration has come about as a result of comments by scientific colleagues who considered studies of the composition and structure of humic substances (HS) a waste of time and never likely to bring worthwhile results, and who felt that an awareness of the "polymeric and polyelectrolyte nature of

Recent studies of SOC storage and turnover have employed 13 C natural abundance (␦ 13 C) as an in situ Soil organic carbon (SOC) is sensitive to management of tillage, marker of relic and recent SOC pools. Mass concentraresidue (stover) harvest, and N fertilization in corn (Zea mays L.), tions of SOC and the ␦ 13 C signature are sufficient to but little is known about associated root biomass including rhizodeposition. Natural C isotope abundance (␦ 13 C) and total C content, mea-calculate the amount of SOC originating from a C 4 crop sured in paired plots of stover harvest and return were used to estimate (e.g., corn) or from a C 3 crop [e.g., soybean, Glycine corn-derived SOC (cdSOC) and the contribution of nonharvestable max (L.) Merr.] when the initial soil organic carbon biomass (crown, roots, and rhizodeposits) to the SOC pool. Rhizo-(SOC i) has a different 13 C signature than the current deposition was estimated for each treatment in a factorial of three crop (Balesdent et al., 1987). The ␦ 13 C technique has tillage treatments (moldboard, MB; chisel, CH; and no-till, NT), two shown that tillage influences the depth distribution of N fertilizer rates (200 and 0 kg N ha Ϫ1), and two corn residue manage