Soil quality: to regulate or to manage?

The concept of soil quality was conceived in the early 1990s as a parallel to those of air and water quality in response to concerns about soil 'health,' sustainability and environmentally `friendly' crop production. The concept has the potential to be used by researchers to link soil research issues to broader environmental issues when applying for funds. However, unlike air and water, soils have no defined 'pure' state against which measures can be taken and comparisons made. The physical, chemical and biological composition of soils varies widely and no single attribute or soil type can be established as a standard. The choice of appropriate soil properties and their standards depends on the use to which the soil is put. We suggest concentrating on quality management of the soil, rather than managing generically-chosen soil properties, collectively called soil 'quality'. Quality management puts the onus on managers to use the technical tools that are readily available to manage soils and landscapes, and on scientists to develop new tools

Deficiencies in the soil quality concept and its application

Soil quality is a concept that has deeply divided the soil science community. It has been institutionalized and advocated without full consideration of concept weaknesses and contradictions. Our paper highlights its disfunctional definition, flawed approach to quantification, and failure to integrate simultaneous functions, which often require contradictory soil properties and/or management. While the concept arose from a call to protect the environment and sustain the soil resource, soil quality indexing as implemented may actually impair some soil functions, environmental quality, or other societal priorities. We offer the alternative view that emphasis on known principles of soil management is a better expenditure of limited resources for soil stewardship than developing and deploying subjective indices which fail to integrate across the necessary spectrum of management outcomes. If the soil quality concept is retained, we suggest precisely specifying soil use, not function or capacity, as the criteria for attribute evaluation. Emphasis should be directed toward using available technical information to motivate and educate farmers on management practices that optimize the combined goals of high crop production, low environmental degradation, and a sustained resource

US hegemony and the origins of Japanese nuclear power : the politics of consent

This paper deploys the Gramscian concepts of hegemony and consent in order to explore the process whereby nuclear power was brought to Japan. The core argument is that nuclear power was brought to Japan as a consequence of US hegemony. Rather than a simple manifestation of one state exerting material ‘power over' another, bringing nuclear power to Japan involved a series of compromises worked out within and between state and civil society in both Japan and the USA. Ideologies of nationalism, imperialism and modernity underpinned the process, coalescing in post-war debates about the future trajectory of Japanese society, Japan's Cold War alliance with the USA and the role of nuclear power in both. Consent to nuclear power was secured through the generation of a psychological state in the public mind combining the fear of nuclear attack and the hope of unlimited consumption in a nuclear-fuelled post-modern world

Modelling nutrient uptake: A possible indicator of phosphorus deficiency

An understanding of the processes controlling soil nutrient supply and plant uptake has led to process-based models that can predict nutrient uptake and the concentration gradient that develops at the root surface. By using this information, it may be possible to develop an indicator of soil phosphorus status based on the predicted uptake and/or concentration of phosphorus (P) at the root surface. To identify the potential for such a test, the relationships between model output and observed plant growth were examined using data from a published experiment. The experiment was initially designed to investigate the relationship between common indices of soil-available P and the growth of maize (Zea mays) in 26 surface soils from Queensland. There was a high correlation between observed and predicted P uptake, and between relative dry matter yield and predicted P uptake. The predicted concentration of P at the root surface was also highly correlated with P uptake and dry weight increase. It is hypothesised that the short growth period (25 days) was responsible for the high correlation between P uptake and measured soil solution P. The hypothesis that a predicted concentration of P at the root surface or predicted P uptake may be valuable indicators of P deficiency in the longer term still remains to be tested

Determining and managing maize yield gaps in Rwanda

Smallholder maize growers are experiencing significant yield gaps due to sub-optimal agricultural practices. Adequate agricultural inputs, particularly nutrient amendments and best management practices, are essential to reverse this trend. There is a need to understand the cause of variations in maize yield, provide reliable early estimates of yields, and make necessary recommendations for fertilizer applications. Maize yield prediction and estimates of yield gaps using objective and spatial analytical tools could provide accurate and objective information that underpin decision support. A study was conducted in Rwanda at Nyakiliba sector and Gashora sector located in Birunga and Central Bugesera agro-ecological zones, with the objectives of (1) determining factors influencing maize yield, (2) predicting maize yield (using the Normalized Difference Vegetation Index (NDVI) approach), and (3) assessing the maize yield gaps and the impact on food security. Maize grain yield was significantly higher at Nyakiliba (1.74 t ha−1) than at Gashora (0.6 t ha−1). NDVI values correlated positively with maize grain yield at both sites (R2 = 0.50 to 0.65) and soil fertility indicators (R2 = 0.55 to 0.70). Maize yield was highest at 40 kg P ha−1 and response to N fertilizer was adequately simulated at Nyakiliba (R2 = 0.85, maximum yield 3.3 t ha−1). Yield gap was 4.6 t ha−1 in Nyakiliba and 5.1 t ha−1 in Gashora. Soil variables were more important determinants of social class than family size. Knowledge that low nutrient inputs are a major cause of yield gaps in Rwanda should prioritize increasing the rate of fertilizer use in these agricultural systems

Generalized model for plantation production of Eucalyptus grandis and hybrids for genotype-site-management applications

The use of process-based modelling of wood production in forest plantation has increased in recent decades amongst researchers and forest companies. Although, such models are used by several plantation researchers and managers, improved options and sensitivity to soil characteristics, genotype, and management options are desirable. A new generation of forest productivity modelling needs to extend previous capabilities and incorporate modern software engineering technologies. Our objective was to develop and evaluate an Agricultural Production Systems sIMulator (APSIM) Next Generation model for simulating the growth of Eucalyptus grandis and hybrids with or of E. globulus and E. urophyylla. The model simulates stem, canopy and root development, resource capture and use (light, water, N), and C and N allocation as mediated by climate, soil, genotype physiological characteristics and management. Tree dimensions (stem diameter, height, volume) are calculated as empirical functions of above-ground biomass. Datasets used for model calibration or independent evaluation were from diverse conditions in Australia (5 sites) and Brazil (13 sites), and at several of these sites there were treatments for fertilizer, irrigation or genotype. For the calibration and evaluation datasets, model performance was very good for above-ground biomass (Nash Sutcliffe Efficiency, NSE = 0.96 and 0.84 respectively). Notwithstanding this general performance, and as an example, local calibration improved performance in one of the independent test datasets, suggesting that applications of the model for specific sites or clones may benefit from parameterization to local conditions. Simulation of management for weed cover, N fertilizer and genotype are also demonstrated. As the model performed well and has high flexibility, it warrants consideration by forest plantation managers and researchers for knowledge synthesis and operational productivity predictions of Eucalyptus and other plantation genotypes

Deficiencies in the soil quality concept and its application

Soil quality is a concept that has deeply divided the soil science community. It has been institutionalized and advocated without full consideration of concept weaknesses and contradictions. Our paper highlights its disfunctional definition, flawed approach to quantification, and failure to integrate simultaneous functions, which often require contradictory soil properties and/or management. While the concept arose from a call to protect the environment and sustain the soil resource, soil quality indexing as implemented may actually impair some soil functions, environmental quality, or other societal priorities. We offer the alternative view that emphasis on known principles of soil management is a better expenditure of limited resources for soil stewardship than developing and deploying subjective indices which fail to integrate across the necessary spectrum of management outcomes. If the soil quality concept is retained, we suggest precisely specifying soil use, not function or capacity, as the criteria for attribute evaluation. Emphasis should be directed toward using available technical information to motivate and educate farmers on management practices that optimize the combined goals of high crop production, low environmental degradation, and a sustained resource