Tuesday, November 17, 2015

Knowing nutrient mobility is helpful in diagnosing plant nutrient deficiencies

Nutrients important for plant growth vary in their ability to move within the plant. Knowing how they move can be helpful when diagnosing deficiency problems.

Friday, November 13, 2015

Biochar (Carbonized Organic Matter)
Understand what is Biochar and its importance as an effective soil amendments with multiple benefits to the agriculture sector.
Know more on Biochar as a soil amendment

Introduction 
Soils have the ability to absorb carbon dioxide and influence its concentration in the atmosphere. Biochar can be used to increase the ability of soils to sequester carbon and simultaneously improve soil health. The goal of this paper is to introduce the concept and origins of biochar, discuss its production process, potential uses, and the benefits and costs of biochar in its key roles in agriculture and climate change mitigation.

What is biochar? 
Biochar is just charcoal made from biomass—which is plant material and agricultural waste—hence the name ‘biochar’. It is a fine-grained charcoal produced from pyrolysis: the slow burning of organic matter in a low- or no-oxygen environment. What differentiates biochar from charcoal is its purpose; it is produced as an additive to soils, mainly to improve nutrient retention and carbon storage. 1 Although the history of biochar extends thousands of years, its science is still relatively poorly understood. History of biochar The term ‘biochar’ was coined in recent times, but the origins of the concept are ancient.2 Throughout the Amazon Basin there are regions—up to two metres in depth—of terra preta. 3 This is a highly fertile dark-coloured soil that has for centuries supported the agricultural needs of the Amazonians. Analyses of the dark soils have revealed high concentrations of charcoal and organic matter, such as plant and animal remains (manure, bones and fish). Terra preta’s productivity is due to good nutrient retention and a neutral pH, in areas where soils are generally acidic.4 Interestingly, terra preta exists only in inhabited areas, suggesting that humans are responsible for its creation. What has not been confirmed is how terra preta was created so many years ago. Many theories exist. A frontrunner is the suggestion that ancient techniques of slash-and-char are responsible for the dark earth. Similar to slash-and-burn techniques, slash-and-char involves clearing vegetation within a small plot and igniting it, but only allowing the refuse to smoulder (rather than burn). 5 Combined with other biomass and buried under a layer of dirt, the smouldering char eventually forms terra preta. 6 It is from these hypotheses of early slash-and-char practices that modern scientists have developed methods for producing biochar.

Biochar production 
The biochar production process begins with biomass being fed into a pyrolysis kiln—a furnace that burns with little or no oxygen. The biomass could be crop residue, wood and wood waste, certain animal manure, or various other organic materials. At the end of this, two main products come out of the kiln.7 The first is biochar, usually representing about 50 per cent of the carbon content of the biomass. The other is biofuel. The biofuel is often syngas, which is a mixture of mainly hydrogen and carbon monoxide, with a little carbon dioxide. The proportions of the three gases vary according to the processes used to create the syngas. However, the important point is that syngas is combustible and so can be used as a fuel source. Depending on the process, the biofuel from the kiln could also be biooil, which can be used as a substitute for diesel in some engines. The pyrolysis occurs at temperatures below 700˚C; but some parameters can be altered, such as the rate of pyrolysis, or the quantity of oxygen. Generally, faster pyrolysis results in more oils and liquids, slower pyrolysis produces more syngas. Minimising the oxygen present during pyrolysis optimises the production of biochar.8 Pyrolysis can be followed by a second stage: gasification. Gasification liberates more energyrich syngases from the char (usually hydrogen-based). There may also be a ‘gas cleanup’ stage to remove some of the particulates, hydrocarbons and soluble matter from the gas.9 The biofuel generated from the pyrolysis process can be used to create the electricity needed to power the kiln or secondary stages of the process. So it is possible for the system to run autonomous of external power sources. The pyrolysis process described is summarised in Figure 1.






Simplified pyrolysis process flow diagram An important advantage of biochar is that it can be produced either from small, simple mobile units or from larger, stationary ones. Small-scale systems for biomass inputs of 50 to 1000 kilograms per hour can be used on farms, while large units of up to 8000 kilograms per hour can be operated by large industries.10 There are potentially three broad types of pyrolysis systems: • central pyrolysis plants for processing all the biomass in a region. • lower-tech pyrolysis kilns for individual farmers or small groups of farmers (these kilns may not include some secondary stages such as the gasification or gas cleanup). • pyrolysis trucks powered by syngas that could be driven around for processing biomass within a region. The biochar and bio-oil would be transported on the truck back to the customers. 

Friday, October 30, 2015

Saturday, October 3, 2015

Crop production depends heavily on having nutrients readily available for plant uptake. Management of all nutrient sources, including commercial fertilizer, compost and manure, within the constraints of farm production systems and operational goals are prerequisite for both profitable crop production and environmental sustainability. 
Inappropriate management of these sources can lead to a reduced economic return and environmental degradation of both, surface and ground water. It is imperative that nutrient management planning activities are recognized and carried out.
• Soil fertility reflects the physical, chemical and biological state of soil.
• Soil fertility can be defined in relation to the plants that grow naturally or are introduced into soil.
• Knowledge of the origin of soil helps to predict the level of soil fertility prior to land management.
• Soil disturbance alters the physical, chemical and biological components of soil fertility either directly or indirectly.
• Assessing the biological fertility of soil is not simple and this book provides an overview of why this is so.

Tuesday, September 29, 2015

Historical Development of Plant Nutrition

    The development of the knowledge on the mineral nutrition of plants begins between the 17th and 18th centuries when some European naturalists gave the first experimental evidences of what had been empirically known for about two millennia. The works of Hales and Ingenhousz were of absolute importance in relation to the transport of water and solutes, and assimilation of "fixed air" (carbon dioxide), respectively. 

      The early chemistry introduced by Lavoisier benefited the first physiologists Senebier and De Saussure to reject the "theory of humus", which imposed the soil as the unique source of carbon. During the first half of the 19th century, Sprengel and Liebig investigated on the problems related to some indispensable mineral salts, while Boussingault and Ville attempted to prove the nitrogen fixation from air without giving any convincing evidence. Liebig was the pioneer of the agricultural chemistry: he epitomised the knowledge of that period by imposing the so-called "law of the minima", already acknowledged by Sprengel, and patronised the use of mineral fertilisers in Europe by devising several formulas of mineral manure. He, however, did not recognise the needs of external supplies of nitrogen salts for the crops, in open dispute with the English school of Lawes and Gilbert, who were instead convinced assertors of such needs.

        At the end of the 19th century Hellriegel showed that leguminous plants presenting peculiar nodules on their roots could really fix the gaseous nitrogen. From these nodules Beijerinck and Prazmowski isolated for the first time some bacteria which were recognised as the real agents fixing nitrogen. This discovery was of fundamental importance for plant nutrition, only second to the discovery of photosynthesis. Another basic contribution came from early research of Sachs on plants grown on aqueous solutions: these techniques allowed to impose the concept of "essential elements", which was fixed as a principle by Arnon and Stout in 1939. This principle benefited further research concerning the effects of states of deficiency on plant growth and development through investigation on the anatomical, histologic and biochemical nutritional disorders of plants.


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Historical development of plant nutrition


The Father of Fertilizer