선택한 단어 수는 입니다.
최소 단어 이상 선택하여야 합니다.
최소 단어 이상 선택하여야 합니다.
선택한 단어 수는 30입니다.
최대 10 단어까지만 선택 가능합니다.
최대 10 단어까지만 선택 가능합니다.
제안 방법
- In the experiments, soil samples with 3 or 4 replications were collected to a depth of 120 cm with a hydraulic core-sampling machine at periodic intervals for analysis. Soil core samples were systematically collected at the sampling sites within each plot : halfway between adjacent plant rows, and directly in the row to estimate spatial variability as a function of distance from path of the applicator knife.
- In the experiments, soil samples with 3 or 4 replications were collected to a depth of 120 cm with a hydraulic core-sampling machine at periodic intervals for analysis. Soil core samples were systematically collected at the sampling sites within each plot : halfway between adjacent plant rows, and directly in the row to estimate spatial variability as a function of distance from path of the applicator knife.
- This experiment represents a cooperative effort between ARS personnel and operational commercial farms using practices typical of those in the central corn belt. The cooperating farmers allowed USDA scientists unrestricted access to representative fields over the three-year experimental period reported in this study; the measurements reported here were designed to monitor the soil water balance and the fate of nutrients applied to the soil with a view to evaluating the contribution of typical farmers practices to environmental contamination.
- Therefore, to find optimal N management practices for use with the different tillage systems and to minimize nitrate leaching losses, one must understand the fate of various N forms in soil, and how N availability to plants affects numerous parameters, especially soil water uptake. The objectives of this study were to monitor changes of soil water content, and nitrate concentrations under different tillage systems on commercial farms in Central Illinois, and to identify the effects of fertilizer, soil type, and tillage systems on nitrate leaching in soils following inorganic N fertilizer application, with a view to estimating optimal N fertilizer application rates and timing to minimize environmental hazards.
대상 데이터
- The study was conducted in cooperation with two privately-owned commercial farms located in central Illinois near the city of Bloomington. The study was begun on farm A in 1993 and on farm B in 1994. The soil series in farm A consisted of (a) Flanagan silt loam (a fine, montmorillonitic, mesic, Aquic Argiudoll) and (b) Saybrook silt loam (a fine silty, mixed, mesic Typic Argiudoll).
- A field study was initiated in the spring of 1993 and continued for two growing seasons. The study was conducted in cooperation with two privately-owned commercial farms located in central Illinois near the city of Bloomington. The study was begun on farm A in 1993 and on farm B in 1994.
- Two tillage systems, conventional tillage (CT) and no tillage (NT), were used in this study. CT involved chiselplowing, leaving residue on the soil surface, while in the NT system, the soil surface was left undisturbed from one harvest to next.
데이터처리
- Data reduction for statistical analysis of the nitrate concentration was done with the SAS system (SAS Institute, 1985) and Super ANOVA (Gagnon, et al., 1989). Separated analyses of variance for nitrate concentration were performed for each year.
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