Soil fertility index

Values of a soil fertility index (SFI, Moran et al. 2000) or a soil evaluation factor (SEF, Lu et al. 2002) were calculated to quantify the intensity of the land degradation. SFI showed the applicability to measuring soil quality and to predicting succession rate of secondaiy tropical forest (Moran et al. 2000). The following equation was used to calculate SFI values (Lu et al. 2002). 

Table 3. Soil fertility index (SFI) degradation or soil evaluation factor (SEF) reflecting the land ...

Ecosystem productivity is an index integrating the cumulative effects of many processes and interactions which proceed simultaneously in the system. Whether or not a relation exists between soil fertility and forest productivity is still under discussion (Proctor 1992, Silver 1994, Thompson et al. 1992). There is, however, no doubt that soil fertility influences input/output budgets, and that soil fertility influences the rate of recovery of the forest ecosystem after disturbance (Bruijnzeel 1992). 

Potassium nitrate is being used increasingly on intensive crops such as tomatoes, potatoes, tobacco, leafy vegetables, citms, and peaches. The properties that make it particularly desirable for these crops are low salt index, nitrate nitrogen, favorable N K20 ratio, negligible CU content, and alkaline residual reaction in the soil. The low hygroscopicity of KNO (Table 9) leads to its use in direct appHcation and in mixtures. It is an excellent fertilizer but the high cost of production limits its use to specialty fertilizers. 

Doelman P, Jansen E, Michels M, Van-Til M (1994) Effects of heavy metals in soil on microbial diversity and activity as shown by the sensitivity-resistance index, an ecological relevant parameter. Biol Fertil Soils 17 177-184... 

The second reason for acid-digestion is the determination of the total soil elemental content of, e.g. potassium, phosphorus or trace elements. This is seldom done for potassium in normal soil samples, mainly because the total K in soils is of no value as an index to the availability of K to plants, nor is it always of value in tracing the movement or accumulation of applied fertilizer K (Pratt, 1965). The unreactive soil phosphorus is obtained by subtracting the naturally leached reactive phosphorus from the total phosphorus, and a method for determining the latter by extraction with sulphuric acid and potassium persulphate is cited by Turner and FHaygarth (2000). They analysed... 

There are many different types of soil, and extractant formulations have been fine-tuned to suit the soil. The particular extractant may also be chosen on the basis of familiarity over the years, and because it is easier to compare results with those previously obtained, and hence make recommendations to correct deficiencies based on experience. Usually one is not interested in the total amount of a soil nutrient, rather in the amount that is in a form available to the roots of the plant. Regional advisory laboratories over a long period may have developed index tables relating to the found concentration of nutrient in local soil types and the corrective amount of fertilizer required. It would probably be wise to adopt the same methods that have been used to... 

The methods of analysis for phosphate solubility are not absolute, but empirical that is, they are based on practical experience. For example, the neutral ammonium citrate method is favoured in the USA because it has received over 100 years of study and experimentation, and provides an index correlating the laboratory results with the fertilizing value of water-insoluble phosphates under the conditions prevailing in the principal farming regions of the country. The particular solvent is therefore not an attempt to accurately reproduce the properties of the soil solution in the immediate vicinity of the... 

The influence of application of Idaho phosphate fertilizer on pH and cadntium availability index (CAl) of the bulk and rhizosphere soils collected at 2- and 7-week crop growth stages. Modified from Krishnamurti et al. (1996)... 

Because chemical fertilizers are salts, the overapplication of soluble fertilizers can cause the soil solution to have high osmotic pressure and inhibit water uptake by seeds or plants. For this reason, soluble fertilizers (mainly the N and K forms) cannot be applied in large amounts with seeds or close to plants. A salt index was developed years ago to pro e relative guid-... 

According to the research of Pryanishnikov All-Russian Scientific Research Institute of Agrochemistry together with Lomonosov Moseow state University unilateral use of mineral fertilizer decreased the total number of microorganisms in soil and Shannon index biodiversity (Table 20.3). 

From the above is follows that traditional soil test, for example, moving phosphorus determination as index of its effective fertility didn t create an adequate representation of its natural fertility. 

On fertile soils there is little response to nitrogen, phosphate and potash and at SNS index 1 the crop has a nitrogen requirement of 50-100 kg/ha, phosphate 30kg/ha and potash lOkg/ha at index 2. 

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