Influence of yield on costs and income in agricultural production

Cover title

Cost of producing cotton in southeast Missouri, 1941

Cover title.Includes bibliographical references

Biogeochemical controls and isotopic signatures of nitrous oxide production by a marine ammonia-oxidizing bacterium

Nitrous oxide (N2O)[N subscript 2 O] is a trace gas that contributes to the greenhouse effect and stratospheric ozone depletion. The N2O [N subscript 2 O] yield from nitrification (moles N2O-N [N subscript 2 O - N] produced per mole ammonium-N consumed) has been used to estimate marine N2O [N subscript 2 O] production rates from measured nitrification rates and global estimates of oceanic export production. However, the N2O [N subscript 2 O] yield from nitrification is not constant. Previous culture-based measurements indicate that N2O [N subscript 2 O] yield increases as oxygen (O2) [O subscript 2] concentration decreases and as nitrite (NO2−) [NO subscript 2 overscore] concentration increases. Here, we have measured yields of N2O [N subscript 2 O] from cultures of the marine β-proteobacterium [beta-proteobacterium] Nitrosomonas marina C-113a as they grew on low-ammonium (50 μM)[50 mu M] media. These yields, which were typically between 4 × 10−4 [10 superscript -4] and 7 × 10−4 [10 superscript -4] for cultures with cell densities between 2 × 102 [10 super script 2] and 2.1 × 104 [10 superscript 4] cells ml−1 [ml superscript -1], were lower than previous reports for ammonia-oxidizing bacteria. The observed impact of O2 [O subscript 2] concentration on yield was also smaller than previously reported under all conditions except at high starting cell densities (1.5 × 106 cells ml−1) [1.5 x 10 superscript 6 cells ml superscript -1], where 160-fold higher yields were observed at 0.5% O2 [O subscript 2](5.1 μM [mu M] dissolved O2 [O subscript 2]) compared with 20% O2 [O subscript 2] (203 μM [mu M] dissolved O2 O subscript 2]). At lower cell densities (2 × 102 [10 superscript 2] and 2.1 × 104 [10 superscript 4] cells ml−1 [ml superscript -1]), cultures grown under 0.5% O2 [O subscript 2] had yields that were only 1.25- to 1.73-fold higher than cultures grown under 20% O2 [O subscript 2]. Thus, previously reported many-fold increases in N2O [N subscript 2 O] yield with dropping O2 [O subscript 2] could be reproduced only at cell densities that far exceeded those of ammonia oxidizers in the ocean. The presence of excess NO2− [NO subscript 2 overscore] (up to 1 mM) in the growth medium also increased N2O [N subscript 2 O] yields by an average of 70% to 87% depending on O2 [O subscript 2] concentration. We made stable isotopic measurements on N2O [N subscript 2 O] from these cultures to identify the biochemical mechanisms behind variations in N2O [N subscript 2 O] yield. Based on measurements of δ15Nbulk [delta superscript 15 N superscript bulk], site preference (SP = δ15Nα−δ15Nβ [delta superscript 15 N superscript alpha - delta superscript 15 N superscript beta]), and δ18O [delta superscript 18 O] of N2O [N subscript 2 O] (δ18O-N2O [delta superscript 18 O - N subscript 2 O]), we estimate that nitrifier-denitrification produced between 11% and 26% of N2O [N subscript 2 O] from cultures grown under 20% O2 [O subscript 2] and 43% to 87% under 0.5% O2 [O subscript 2]. We also demonstrate that a positive correlation between SP and δ18O-N2O [delta superscript 18 O - N subscript 2 O] is expected when nitrifying bacteria produce N2O [N subscript 2 O]. A positive relationship between SP and δ18O-N2O [delta superscript 18 O - N subscript 2 O] has been observed in environmental N2O [N subscript 2 O] datasets, but until now, explanations for the observation invoked only denitrification. Such interpretations may overestimate the role of heterotrophic denitrification and underestimate the role of ammonia oxidation in environmental N2O [N subscript 2 O] production

Why do borrowers pledge collateral? new empirical evidence on the role of asymmetric information

An important theoretical literature motivates collateral as a mechanism that mitigates adverse selection, credit rationing, and other inefficiencies that arise when borrowers hold ex ante private information. There is no clear empirical evidence regarding the central implication of this literature—that a reduction in asymmetric information reduces the incidence of collateral. We exploit exogenous variation in lender information related to the adoption of an information technology that reduces ex ante private information, and compare collateral outcomes before and after adoption. Our results are consistent with this central implication of the private-information models and support the empirical importance of this theory.

The horse and mule outlook

Caption title.Digitized 2006 AES MoU.Includes bibliographical references

The operators' cost of producing some field crops in central Missouri

Publication authorized March 20, 1946.Digitized 2007 AES

Reducing the cost of producing dairy and poultry products in Missouri

Caption title.At head of title: A wartime publication.Digitized 2006 AES MoU

The costs of crop production in Missouri, 1921

Cover title.Includes bibliographical references

The labor required and its distribution in Missouri farm crop production

Publication authorized October 14, 1944.Digitized 2007 AES

Credit scoring and the availability, price, and risk of small business credit

The authors examine the economic effects of small business credit scoring (SBCS) and find that it is associated with expanded quantities, higher average prices, and greater risk levels for small business credits under $100,000. These findings are consistent with a net increase in lending to relatively risky "marginal borrowers" who would otherwise not receive credit, but who would pay relatively high prices when they are funded. The authors also find that 1) bank-specific and industrywide learning curves are important; 2) SBCS effects differ for banks that adhere to "rules" versus "discretion" in using the technology; and 3) SBCS effects differ for slightly larger credits