Compost pellets (PC) are different from non-pelletized composts in various properties including supply and retention of nutrients and production of greenhouse gases because of the micromorphology of PC. Therefore, it
is important to micro-morphologically characterize PC for its proper utilization. We investigated long-term changes in the micromorphology of cattle manure PC after its applica-tion in a soil. The PC grains were applied in a three-types soil core containing a Lowland soil, a Yellow soil, and an Andosol. The soil cores were buried in a field plot of its soil type. After 1, 6, and 18 months, the soil core was sliced into thin sections after solidifying with a polyester resin for the cross-sectional observation. Decomposition of the compost was also investigated using a glass-fiber filter bag method. Results from the investigation were as follows. 1) Weight residual ratio and carbon residual ra-tio of PC decreased rapidly in the first 6 months, and after that the decomposition became slower. 2) With the decom-position of PC, their shape was preserved, whereas their volume decreased. Estimated volume residual ratio of PC was 28 % for Lowland soil, 43 % for Yellow soil, and 39 % for Andosol after 18 months. Voids corresponding to the volume loss of PC by decomposition was formed around each PC grain. 3) PC mixed with the Yellow soil were cross-sectionally divided into curved segments by cracks whereas this separation was not observed in the Lowland soil and Andosol. 4) Internal microstructure of PC did not show a clear temporal change from 1 month to 18 months in any of the examined soils. Microstructure type was mas-sive microstructure to subangular blocky microstructure, with poor separation of peds.
The aim of this study is to evaluate soil water movement and water consumption in crop fields based on the crop root distribution and daily soil evaporation. A nu-merical model based on HYDRUS-1D was introduced to simulate the soil water movement under different distribu-tions of crop root. A concept of dual crop coefficient was used to separately quantify soil evaporation and transpira-tion for the boundary condition of the soil surface and the root extraction. Soil evaporation reduction coefficient was introduced to estimate the soil evaporation reduction with the decrease of soil water content. Field measurement was performed in a broccoli field to verify the model assump-tion. Simulated volumetric water contents near the surface assuming a uniform root distribution were quite different from observed data. Hence simulated and measured wa-ter consumptions according to the soil moisture depletion method did not agree well. When the root growth process and the soil evaporation reduction coefficient were taken in account in the soil water analysis, simulated volumetric water content and water consumption had good agreement with the measured ones.
It is essential to properly determine soil hy-draulic properties (soil water retention curve and unsatu-rated hydraulic conductivity) to adequately predict soil wa-ter movement in a field when the daily water consumption for upland irrigation planning is determined based on the flow simulation. The soil hydraulic parameters for three layers from the surface were inversely determined based on the observed soil water contents at several depths in
a bare field as an objective function. In order to obtain appropriate soil hydraulic parameters reproducing the ob-served soil contents, it was necessary to give an appropriate bottom boundary condition, to use laboratory-determined water retention parameter values and saturated hydraulic conductivity as initial values for the inverse solution, to es-timate at least the saturated hydraulic conductivity, but not to include the retention parameters and the saturated hy-draulic conductivity in an objective function to give greater flexibility in the optimization, and to estimate parameters for the three layers at the same time. The daily water con-sumptions for the grape tomato cultivation condition were evaluated according to the moisture depletion method for simulated water content profiles using the estimated soil hydraulic parameters. The simulated daily consumptions were mostly approximately 2 mm d−1 greater than the con-sumption values based on the measured soil water content profiles. However, simulated and measured values agreed well within 1 mm d−1 differences for some periods.
How can we improve the acceptance and inclu-sion of science in public debate and decision making? In this article, I argue that scientists have to do a better job of understanding what drives people to make decisions. By listening to stakeholders concerns, we can improve our sci-ence and its impact.