Fertiliser liming

Calcium cyanamide (lime nitrogen) has been used as a fertiliser (6). It hydrolyses ia moist soil to produce ammonia ... 

Basic slag used to be a popular fertiliser for supplying phosphate, but it also had liming value and contained some trace elements. However, the older steel-making processes are now out-of-date and basic slag is much less freely available. The consequence of this is that soils in Britain are becoming more acidic. 

Zaman M, Nguyen ML. Effect of lime or zeolite on NzO and N emissions from a pastoral soil treated with urine or nitrate-N fertiliser under field conditions. Agriculture Ecosystems and Environment. 2010 136 254—261. 

The practical significance of such competition evolves from the experience that silicate and (anionic) humics can increase the efficiency of phosphate fertiliser because these compounds occupy sites suitable for phosphate adsorption (Kingston et ak, 1968 Schwertmann, 1995). Hydroxyl is another anion that competes effectively with adsorbing anions, owing to its location in the inner Helmholz layer. The release of adsorbed phosphate after liming a soil or after inflow of acidic surface soil into weakly alkaline surface waters due to erosion, can be considered as the result of competition between OH and phosphate ions. 

There have been many attempts to reduce the migration of toxic metals from soils, and at the same time improve the appearance of derelict sites by the introduction of metal-tolerant ecotypes (Bradshaw et al., 1965 Gemmel, 1977 Bradshaw and Chadwick, 1980). Many such sites are poor in micronutrients and must first be treated with soil amendments such as lime and fertilisers. The maintenance of plant cover at such sites minimises soil erosion and reduces contamination from wind-blown dust. It has... 

The phosphates of lime are the most valuable natural fertilisers and raw material of the fertiliser and phosphorus industry, which uses also to a less extent phosphates of aluminium and the apatites. Over 80 per cent, of the easily decomposible phosphorites mined are used in the preparation of superphosphate or other fertilisers (1980). 

Since the phosphorus compounds which are used in the arts, as well as phosphatic fertilisers, are derived from the decomposition of phosphates of lime, and the interactions of these are also of importance in biochemistry, a short account of the best investigated of these compounds will be given here. ... 

The System Lime and Phosphoric Acid —Solubility of Calcium Phosphates— Conditions of Formation of Basic and Acid Calcium Phosphates—Composition of Solutions Saturated with Calcium Hydrogen Phosphates—Equilibria between Solid Phases and Solutions at Various Temperatures—Changes during Neutralisation—The Acid Phosphates—Manufacture of Superphosphate—Retrogression—Treatment of Special Ores—Phosphoric Acid— Commercial Preparation and Extraction from Rook—The History and Technology of Superphosphate Manufacture—Mixed and Concentrated Phosphorio Fertilisers—Potassium Phosphates—Ammonium Phosphates. 

Approved inputs are listed in Annex II of the Regulation although nearly all require permission from the certifying body before they can be used. Approved fertilisers and soil conditioners include low soluble materials such as rock phosphate and lime, as well as animal manures and by-products such as bone meal and hoof/hom meal. More soluble materials such as blood meal, wood ash and potassium sulphate are also allowed, again following approval from the certification body. 

The resulting dark-colored mixture of calcium cyanamide and carbon is known as lime nitrogen (Kalkstickstoff) and is used in fertilisers. If steam is passed through it, it yields ammonia. 

Macronutrients include N, K, PO3 and lime and are usually applied to the soil as natural or artificial fertilisers. The effects of additional fertilisers on medicinal plant productivity is generally beneficial, but scientific results have often revealed contradictory results and each plant must be investigated separately to determine the optimum level and frequency of fertiliser application. 

The benefits of liming soils with marls and soft chalks was known to the Romans in the first century A.D. Pliny reported that the Ubians, north of Mainz, used white earth (a calcarious marl) to fertilise their fields. 

Some of the lime products complying with the UK s Fertiliser Regulations [30.3] are listed in Table 30.2. While they are characterised in terms of grading and MgO content, the only declaration required is the neutralising value. 

Compost — the process of composting organic matter can be accelerated by alternately adding about 5 % of hydrated lime and 5 % of a nitrogenous fertiliser to layers of compost. The hydrated lime provides an alkaline environment in which the fertiliser catalyses the conversion of the compost into humus. 

Compound fertilisers (including calcium nitrate and calcium ammonium nitrate) sometimes contain 1 to 2 % of dolomitic hydrated lime. The lime confers similar benefits to pulverised dolomitic limestone (see section 10.3). 

Hydroxyapatite is added in amounts of 1 to 2 % as an anti-caking agent in table salt, sugar and fertilisers. It is also used in toothpaste in conjunction with dicalcium phosphate to modify the polishing properties. The slaked lime should, therefore, meet strict quality requirements (Table 31.2). 

Commercial fertilisers are assigned an NPK value which is the % N, P2O5 and KjO by weight. Another specification is the BPL (bone phosphate of lime) value, which is the P content expressed as % Ca3(P04)2. Available phosphoric acid or APA is a measure of the P2O5 available to plants, as indicated by an empirical solubility test. Unavailable phosphoric acid is usually expressed as the portion of the fertiliser which is insoluble in neutral ammonium citrate. In the United States, available P = total P - citrate - insoluble P (Chapter 14.1). 

E.J. Kamprath and C.D. Foy, Lime-fertiliser interactions in acid soils, Chapter 4 in (9). 

Jaw crusher is useful for crushing lumps of rock phosphate, lime stone required in fertiliser industries, waste treatment etc. They use compressive force between two... 

Lime and fertiliser requirements. Some soil types have different abilities both to hold and release nntrients. Most clay minerals have a negative charge which attracts positively charged ions such as potassium, magnesium and calcium. This is called the cation exchange capacity. The presence of these charged sites affects the availability of nutrients. Sand and silt are relatively inert. Different soil textures with the same level of acidity have different recormnendations for the application of lime. This is due to differences in the cation exchange capacity of the soil. 

Abstract This chapter explains the importance of feeding crops and ensuring that soil fertility is maintained. It discusses the main elements required by crops, both major and trace. It explains why liming is so important for crop nutrition. It deals with the calculations and sources of information needed to accurately decide on fertiliser application rates, and cost them. It describes the materials used on-farm as fertilisers and explains the differences between straights, compounds and blends, as well as dealing with liquids and solid fertilisers. There is a section on the use of oiganic manures and slurries and how to make best use of them. Finally, the chapter deals with the effect of fertilisers on the environment, during both their manufacture and application. 

Ammonium nitrate lime (21-26% N). This granular fertiliser is a mixture of ammonium nitrate and lime. It is sold under various trade names. Because of the calcium carbonate present it does not cause acidity when added to the soil. 

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