Much has been written about theory and practice in the law, and the tension between practitioners and theorists. Judges do not cite theoretical articles often; they rarely "apply" theories to particular cases. These arguments are not revisited. Instead the Essay explores the working and interaction of theory and practice, practitioners and theorists. The Essay starts with a story about solving a legal issue using our intellectual tools - theory, practice, and their progenies: experience and "gut." Next the Essay elaborates on the nature of theory, practice, experience and "gut." The third part of the Essay discusses theories that are helpful to practitioners and those that are less helpful. The Essay concludes that practitioners theorize, and theorists practice. They use these intellectual tools differently because the goals and orientations of theorists and practitioners, and the constraints under which they act, differ. Theory, practice, experience and "gut" help us think, remember, decide and create. They complement each other like the two sides of the same coin: distinct but inseparable.

Of Theory and Practice

Biochar amendment ameliorates soil properties and promotes Miscanthus growth in a coastal saline-alkali soil

Effects of biochar on uptake, acquisition and translocation of silver nanoparticles in rice (Oryza sativa L.) in relation to growth, photosynthetic traits and nutrients displacement.

The individual role of biochar, compost and PGPR has been widely studied in increasing the productivity of plants by inducing resistance against phyto-pathogens. However, the knowledge on combined effect of biochar and PGPR on plant health and management of foliar pathogens is still at juvenile stage. The effect of green waste biochar (GWB) and wood biochar (WB), together with compost (Comp) and plant growth promoting rhizobacteria (PGPR; Bacillus subtilis) was examined on tomato (Solanum lycopersicum L.) physiology and Alternaria solani development both in vivo and in vitro. Tomato plants were raised in potting mixture modified with only compost (Comp) at application rate of 20% (v/v), and along with WB and GWB at application rate of 3 and 6% (v/v), each separately, in combination with or without B. subtilis. In comparison with WB amended soil substrate, percentage disease index was significantly reduced in GWB amended treatments (Comp + 6%GWB and Comp + 3%GWB; 48.21 and 35.6%, respectively). Whereas, in the presence of B. subtilis disease suppression was also maximum (up to 80%) in the substrate containing GWB. Tomato plant growth and physiological parameters were significantly higher in treatment containing GWB (6%) alone as well as in combination with PGPR. Alternaria solani mycelial growth inhibition was less than 50% in comp, WB and GWB amended growth media, whereas B. subtilis induced maximum inhibition (55.75%). Conclusively, the variable impact of WB, GWB and subsequently their concentrations in the soil substrate was evident on early blight development and plant physiology. To our knowledge, this is the first report implying biochar in synergism with PGPR to hinder the early blight development in tomatoes.

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Role of biochar, compost and plant growth promoting rhizobacteria in the management of tomato early blight disease.

China with large area of land planted with crops are suffering secondary salinization in coastal area for the lack of fresh water and saltwater intrusion to the groundwater. The purpose of this study was to investigate the effects of biochar (BC) and fulvic acid (FA) on the amelioration of coastal saline soil and their impact on crop yields under maize-barley rotation system. A three year field experiment was conducted in a saline soil on a farm in coastal area of east Jiangsu Province, China. A maize-barley rotation system had been carried out for ten years with local conventional management before the experiment. The saline soil was amended with BC at rates of 0, 7.5 t ha−1 (BC1), 15 t ha−1 (BC2) and 30 t ha−1 (BC3) alone or combined with fulvic acid (1.5 t ha−1) compared with control. Fertilizers were applied under normal planting strategies. The BC was added only once during the four growing seasons, and the FA was applied before each sowing. Soil salinity changed significantly during the three year field experiment. This was mainly due to the great quantity of rain during the period of maize cultivation. Although Na+, Cl− and SO42− in BC and /or FA treatments significantly decreased, the pH value increased up to 9.0 as the CO32− + HCO3−content increased. Total organic carbon (TOC) and phosphorus (TP) responded positively to biochar addition rate. BC applied with appropriate rate at 15 t ha−1 (BC2) in combination with FA showed optimal effects on soil salinity amelioration, soil physics properties regulation, soil nutrition improvement and crop yields increase. The TOC and TP was 5.2 g kg−1 and 507 mg kg−1 in BC2 + FA treatment, which were lower than BC3 and BC3 + FA treatments. However, the highest total grain yield was obtained in the BC2 + FA treatment, and the total yield was increased by 62.9% over the CK. This study emphasizes that using combined organic amendment of BC with FA for profitable and sustainable use of salt-affected soils would be practicable.

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Biochar and fulvic acid amendments mitigate negative effects of coastal saline soil and improve crop yields in a three year field trial.

Biochar amendments have been used in agriculture to improve soil fertility and enhance crop productivity. A greenhouse experiment was conducted to test the hypothesis that biochar amendment could also enhance the productivity of salt-affected soils. The trial was conducted over two consecutive growing seasons to investigate the effect of biochar amendment (four application rates as: B1 = 0%, B2 = 2%, B3 = 4%, and B4 = 8% by mass of soil) on yield and quality of tomatoes grown in a silt loam soil using non-saline water (I0 = 0.7 dS m−1) and saline water (I1 = 1 dS m−1; I2 = 3 dS m−1) irrigation. Furthermore, the study investigated the mechanism by which biochar addresses the salt stress on plant. The results showed that soil productivity as indicated by the vegetative growth and tomato yield components was adversely and significantly affected by saline water irrigation (P < 0.05). Tomato yield decreased from 689 ± 35.6 to 533 ± 79.0 g per plant as salinity of irrigation water increased from I0 to I2. Then, biochar amendment increased vegetative growth, yield, and quality parameters under saline irrigation water regimes, and ameliorated the salt stresses on crop growth. The highest (8.73 ± 0.15 and 4.10 ± 0.82 g kg−1) and the lowest (8.33 ± 0.08 and 2.42 ± 0.76 g kg−1) values of soil pH and soil organic matter were measured at B4I0 and B1I2 treatments, respectively. Also, the highest rate of biochar amendment combining with non-saline water irrigation (B4I0) produced tomato with the highest plant photosynthetic (17.08 ± 0.19 μmol m−2 s−1) and transpiration rate (8.16 ± 0.18 mmol H2O m−2 s−1). Mechanically, biochar amendment reduced transient sodium ions by adsorption and released mineral nutrients such as potassium, calcium, and magnesium into the soil solution. Therefore, biochar amendments have the potential in ameliorating salt stress and enhancing tomato production.

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Benefits of soil biochar amendments to tomato growth under saline water irrigation

This paper builds a theoretical model based on a representative peasant household in the neoclassical model, comprehensively considers three types of farmer households in China, and evaluates the effects of the agricultural subsidy policy under equilibrium conditions. Based on the two bottom lines of guaranteeing China’s grain security and ensuring no large-scale return to poverty, this paper uses 2010, 2012, and 2014 tracking survey data from the Mutual Aid Fund for Poverty-Stricken Villages in China to construct an econometric model to evaluate agricultural subsidy effectiveness from the three aspects of farmers’ total sown area, total grain output, and total income. The research draws the following conclusions: (1) Agricultural subsidies can significantly increase the sown area, grain production, and total income of farmers in poverty-stricken areas, which is conducive to improving the farmers’ comprehensive capacity for grain production as well as income, and this conclusion remains valid after performing a series of robustness tests and solving endogeneity problems. (2) The effects of the agricultural subsidy policy are affected by natural conditions, economic development levels, and functional orientation of grain production in different regions, and they have divergent influences on farmers’ total sown area, total output, and total income. (3) Agricultural subsidies boost farmers’ willingness to cultivate grain, reduce land abandonment, and increase the total sown area, total output, and total grain income. The willingness to cultivate grain is an important mechanism that affects the effectiveness of the agricultural subsidy policy.

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The Effectiveness Assessment of Agricultural Subsidy Policies on Food Security: Evidence from China’s Poverty-Stricken Villages

Poor soil quality is affected by salinity, which limits land productivity and sustainable agricultural development in coastal China. Hence, it is essential to choose suitable and efficient approaches to revitalize coastal saline soil quality and improve agricultural productivity. Biochar and polyacrylamide (PAM) have been widely applied as soil amendments to enhance soil structure, but the interactive effects of biochar and PAM on rice growth are unclear. The experiment described in this study was conducted over five consecutive growing seasons (from 2016 to 2020) with biochar (at 0, 32, and 79 t/hm2) and PAM (at 0, 0.6, and 1.6 t/hm2) applications to study the effects of amendments on soil properties, rice photosynthesis, and rice yield in coastal saline land. The soil property results showed that wheat straw biochar and PAM lowered soil total salt and bulk density, but increased the soil organic matter (SOM), mean weight diameter of water-stable aggregates (MWD), and macroaggregate (> 0.25 mm) content. The application of either biochar or PAM increased the rice net photosynthetic rate, transpiration rate, and stomatal conductance. The combined application of 32 t/hm2 biochar + 0.6 t/hm2 PAM increased the net photosynthetic rate by 26.0% and the transpiration rate by 24.8% relative to the control. The application of 32 t/hm2 biochar and 1.6 t/hm2 PAM significantly increased the rice grain yield. The path analysis model showed that spikelets per panicle and canopy gross photosynthesis had strong and significant positive effects on grain yield, whereas soil total salt had a negative effect on grain yield. The combined application of 32 t/hm2 biochar + 0.6 t/hm2 PAM was identified as the most effective for rice growth. Biochar and PAM amendments at an optimal level may enhance soil properties by reducing salinity. These findings indicate that biochar and PAM have the potential to remediate coastal saline soil quality and the environment, which would simultaneously increase the sustainable use of coastal land resources and food production to preserve the ecological environment. 

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Application of biochar and polyacrylamide to revitalize coastal saline soil quality to improve rice growth

Coastal soil is an important reserve land resource. The accurate prediction of soil hydraulic properties plays an important role in understanding the improvement of soil properties after reclamation in coastal areas. With the development of modern mathematical theory, the pore-solid fractal (PSF) model has become an important basis for simulating soil hydraulic properties. The accuracy of PSF model depends on the accurate acquisition of changepoints and fractal dimensions. Previous studies have found that micro-CT scanning combined with image processing could accurately obtain fractal dimensions. However, we still need soil water retention data to determine changepoints, which greatly limits the application of fractal models for estimating soil hydraulic properties. In this case, we determined the relationship between changepoints and soil physical and chemical properties and established a genetic algorithm-support vector regression (GA-SVR) model to predict changepoints. Then an improved PSF model was adopted to predict soil water retention curve in coastal areas of Jiangsu Province based on image processing. The results showed that soil physical and chemical properties changed the soil water movement and changepoints by affecting soil pore distribution. In coastal saline soil, four parameters (BD, silt, EC, SOM) were selected to predict changepoints. The mass fractal dimension (Dm) was mainly influenced by the porosity and the heterogeneity of pore space. The porosity, pore diameter and specific surface area were the determining factors of DS value. Reclamation activities in coastal reclamation area changed Dm value but had no clear effect on DS value. By combining predicted changepoints, measured water content at the suction of changepoints and fractal dimensions, the accuracy of the PSF model had been greatly improved. 

An improved pore-solid fractal model for predicting coastal saline soil hydraulic properties based on changepoints determined by genetic algorithm-support vector regression

Xiaoqin Sun

Papers

Benefits of soil biochar amendments to tomato growth under saline water irrigation

The Effectiveness Assessment of Agricultural Subsidy Policies on Food Security: Evidence from China’s Poverty-Stricken Villages

Application of biochar and polyacrylamide to revitalize coastal saline soil quality to improve rice growth

An improved pore-solid fractal model for predicting coastal saline soil hydraulic properties based on changepoints determined by genetic algorithm-support vector regression