A consideration of fertilizer materials furnishing the three' major plant foods reveals the fact that sources of phosphoric acid and potash have remained almost constant while the sources of nitrogen have undergone decided changes. Superphosphate has been, and probably will continue to be, our main source of phosphoric acid in most fertilizer mixtures. In the year 1900, 79.8 per cent. of the to...

This paper summarizes a series of field experiments that investigated the effects of organic and inorganic nutrients on sweet potato tuber yield in the humid lowlands of Papua New Guinea. In the first experiment, plots were planted with Piper aduncum, Gliricidia sepium and Imperata cylindrica, which were slashed after one year, whereafter sweet potato was planted. Sweet potato yield was lowest ...

The tomato leafminer, Tuta absoluta (Meyrick) is a devastating pest associated with tomato. In this study, effects of tomato plants treated with vermicompost (20, 40, and 60%), humic fertilizer (2, 4 and 6 g/kg soil) and plant growth promoting rhizobacteria (Pseudomonas fluorescens and Bacillus subtilis) were investigated on the life table parameters of T. absoluta in a growth chamber at 25 ± 2...

This study investigated the influence of nitrogen (N) fertilizer and straw on intact amino acid N uptake by soil microorganisms and the relationship between amino acid turnover and soil properties during the wheat growing season. A wheat pot experiment was carried out with three treatments: control (CK), N fertilizer (NF) and N fertilizer plus rice straw (NS). We used stable isotope compound-sp...

Increasing diffuse nitrate loading of surface waters and groundwater has emerged as a major problem in many agricultural areas of the world, resulting in contamination of drinking water resources in aquifers as well as eutrophication of freshwaters and coastal marine ecosystems. Although empirical correlations between application rates of N fertilizers to agricultural soils and nitrate contamin...

Concerns about energy security and climate change have increased biofuel demand, particularly ethanol produced from cellulosic feedstocks (e.g., food crop residues). A central challenge to cropping for cellulosic ethanol is the potential environmental damage from increased fertilizer use. Previous analyses have assumed that cropping for carbohydrate in residue will require the same amount of fe...

The application of hydrological and water quality models is an efficient approach to better understand the processes of environmental deterioration. This study evaluated the ability of the Annualized Agricultural Non-Point Source (AnnAGNPS) model to predict runoff, total nitrogen (TN) and total phosphorus (TP) loading in a typical small watershed of a hilly region near Taihu Lake, China. Runoff...

Synthetic (e.g. urea) and organic fertilizers (e.g. compost) differed markedly in N isotope composition and the greater the difference between organic and synthetic fertilizer the more robust will be the differentiation of crops and vegetable grown under different farming systems. The objective of this study was to compare nitrogen and carbon isotope composition of organic fertilizers and manur...

In this paper we use farmers' actual experiences with changes in rainfall levels and theirresponses to these changes to assess if patterns of fertilizer use are responsive tochanges in rainfall patterns. Using plot and farm level panel data from the centralHighlands of Ethiopia matched with corresponding village level rainfall data; resultsshow that both the current year’s d...