Differences in growth and physiological and metabolic responses among Canadian native and hybrid willows (Salix spp.) under salinity stress

Globally, soil salinization is becoming increasingly prevalent, due to local hydrogeologic phenomena, climate change and anthropogenic activities. This has significantly curtailed current world food production and limits future production potential. In the prairie region of North America, sulfate salts, rather than sodium chloride, are often the predominant cause of soil degradation. In order to amend soil quality, revegetate salt-affected sites and recover economic loss associated with soil salinization, the establishment of short-rotation coppice plantations with willows (Salix spp.) has been suggested as a possible solution. To screen for the best candidates for such an application, 20 hybrid and 16 native willow genotypes were treated with three different salt conditions for 3 months. The treatments were designed to reflect the salt composition and concentrations on North American prairies. Under moderate salinity treatment (7 dS m−1), hybrid willows had better growth, as they established quickly while managing salt transport and mineral nutrition balance. However, native willows showed higher potential for long-term survival under severe salinity treatment (14 dS m−1), showing a lower sodium:potassium ratio in roots and better photosynthetic performance. Two native willow genotypes with high osmotic and salinity tolerance indices, specifically LAR-10 and MJW-9, are expected to show superior potential for remediating salt-affected sites. In addition, we observed significantly higher sulfate/sulfur concentrations in both leaf and root tissues in response to the severe salinity treatment, shedding light on the effect of sulfate salinity on sulfate uptake, and potentially sulfur metabolism in plants.

Soil Acidity and its Management Options in Ethiopia: A Review

Soil acidity is one of the chemical soil degradation problems which affect soil productivity in the Ethiopian highlands. This paper tries to put together soil acidity concept, causes, extent and management practices. Soil acidity is the problem of agricultural activities in Ethiopian highlands (cultivated lands) and is getting an increase. Farmers require simple and sustainable techniques to amend acid soils and improve yields of crops of their choices. Recommendations on reclamation of acid soils need to change with new developments, such as liming, use of acid-tolerant crop varieties, integrated soil fertility management, and using of organic fertilizers. Liming has played an important role in raising soil pH and enhancing crop productivity. In Ethiopia, the gap between potential and actual yield is very wide because of soil acidity and associated nutrient availability. Acidic soils are not responsive to the application of inorganic fertilizers without amendments-it is simply wastage of resources. Thus, developing effective and efficient acid soil management practices is indispensable for enhancing crop productivity and thereby sustaining yield gains. This review focuses on the causes and managements of soil acidity and its subsequent effect on soil fertility and crop yield. It also provides important information on management options to amend soil acidity and improve the entire fertility of soils, and other organic amendments that can be applied to remedy soil acidity to the desired pH level and improve soil quality. Integrated acid soil management enhances the stability of yields and maximizes nutrient use efficiency.

Effect of Paper Mill Sludge on Adsorption and Desorption of Cd(II) and Pb(II) in Paddy Soils

There are high organic matter and cation exchange capacity (CEC) in paper mill sludge, which can be used efficiently to amend soil properties and promote the growth of crops. The batch method was used to investigate effects of paper sludge on adsorption and desorption of Cd (II) and Pb (II) in two types paddy soil (red soil, purple soil), through adding paper sludge to red soil and purple soil. The results showed that isothermal sorption process of Cd (II) and Pb (II) by soils and paper sludge could be well described by Langmuir equation and Freundlich equation, and all coefficients (r) were higher than 0.9. The purple soil had a higher sorption capacity of Cd (II) and Pb (II) than red soil. The sorption capacities of Cd (II) and Pb (II) in soils increased after added paper sludge, and they reached adsorption equilibrium as the percentages of paper sludge were 10%, 1% in red soil and purple soil, respectively. The desorption capacities of Cd (II) and Pb (II) in soils decreased after added paper sludge, and they reached minimum as the percentages of paper sludge were 5%, 2% in red soil and purple soil, respectively. It was better to immobilize Cd (II) and Pb (II) after added paper sludge, thus paper mill sludge can relieve the migration of heavy metals in soil-crop systems. It can provide a new way for safe using of heavy metal contaminated soil and resource utilization of paper sludge.

Effect of organic amendments on sclerotial germination, mycelial growth, and Sclerotium rolfsii-induced diseases

The addition of organic residues to soil is an option to control some soil-borne diseases. Benzaldehyde and powders of kudzu (Pueraria lobata), velvetbean (Mucuna deeringiana), and pine-bark (Pinus elliottii and P. taeda) added to soil could reduce certain soil-borne diseases. This study evaluated the effects of benzaldehyde and the dried powders of kudzu, velvetbean, and pine-bark as soil amendments on germination and formation of sclerotia, on mycelial growth of Sclerotium rolfsii, on plant survival, and disease incidence. The data showed that high amounts of benzaldehyde (0.4 ml kg-1 of soil) and velvetbean (100 g kg-1) inhibited S. rolfsii mycelial growth and sclerotium germination. However, low amounts of benzaldehyde (0.1 ml kg-1), kudzu (25 g kg-1), and pine-bark (25 g kg-1) stimulated mycelial growth and sclerotium germination. Kudzu (25-100 g kg-1) and velvetbean (25-100 g kg-1) inhibited the formation of sclerotia. Nevertheless, benzaldehyde at 0.2 and 0.4 ml kg-1 stimulated the formation of sclerotia. Kudzu (50 and 100 g kg-1) and pine-bark (50 g kg-1) favored the colonization of sclerotia by Trichoderma sp. The numbers of soybean (Glycine max) plants were higher and diseased plants were lower than the non-amend soil in the following treatments: kudzu (50 and 100 g kg-1), velvetbean (50 and 100 g kg-1), and pine-bark (50 g kg-1). Disease severity on tomato (Lycopersicon esculentum) plants was low in soil treated with kudzu or velvetbean (30 and 35 g kg-1) and pine-bark (35 g kg-1). Dried powders of kudzu, velvetbean, or pine-bark added to soil can reduce disease by reducing pathogen inoculum.