This study was designed to evaluate the effect on root dentin microhardness of 2.5% and 6% sodium hypochlorite solutions for various irrigation periods. Forty-two bovine roots were divided into seven groups. The control group was irrigated with saline. The experimental samples were continuously irrigated with 2.5% or 6% NaOCl for 5, 10, or 20 min. Microhardness was measured at depths of 500 mum...

This paper looks at differences in spatial and temporal variation of rice yields in China and Brazil. We find that rice yields in China have converged over time and that rice production has become more and more homogeneous. In contrast, rice yields in Brazil have diverged over time, primarily due to variations in upland rice yields. Three hypotheses are put forward to explain the different beha...

Heavy metal pollution in farmlands is a serious threat to sustainable agricultural development and has become a major agro-ecological problem that has attracted public concern in China. This study proposes a soil–crop collaborative risk assessment model that aims to assess the potential safety risks of heavy metal pollution in farmland soils by considering the concentrations of heavy metals in ...

For a long time, agriculture and recurrent fires have been the main factors promoting diversity changes in Mediterranean areas. We examined the effect of irrigated and non-irrigated crops and fires on the epiphytic lichen diversity of holm oak trees in the Vall d’Albaida region (Valencia, Spain). Lichen diversity was studied by calculating the LDV (Lichen Diversity Value) and the proportion of ...

Pocket gophers were collected from irrigated alfalfa fields (IRR) and non-irrigated fallow fields (NIRR) in Davis, California, for 2 years. Reproduction was continuous in IRR fields with very little seasonal variation in reproductive activity. In contrast, reproduction in NIRR fields occurred primarily during the rainy season (winter and spring). Females in IRR fields produced approximately twi...

We studied the ecological characteristics of 45–50-yr-old subtropical dry forest stands in Puerto Rico that were growing on sites that had been deforested and used intensively for up to 128 yr. The study took place in the Guánica Commonwealth Forest. Our objective was to assess the long-term effects of previous land use on this forest—i.e., its species composition, structure, and functioning. P...

Food security is an important issue that is of concern for all countries around the world. There are many factors which may cause food insecurity including increasing demand, shortage of supply, trade condition, another countries' food policy, lack of money, high food and oil prices, decelerating productivity, speculation, etc. The food self-sufficiency ratio of Taiwan is only 30.6% weighted by...

Protecting water resources from nitrate-nitrogen (NO3-N) contamination is an important public health concern and a major national environmental issue in China. Loss of NO3-N in soils due to leaching is not only one of the most important problems in agriculture farming, but is also the main factor causing nitrogen pollution in aquatic environments. Three typical intensive agriculture farmlands i...

Inorganic C reactions are among the most important chemical reactions that occur in irrigated soils and may contribute to the total amount of C sequestered in those soils. Because CO2 can escape from soils to the atmosphere or return to precipitate carbonate minerals, soils are open systems with regard to inorganic C. We measured inorganic and organic C stored in southern Idaho soils having lon...