Groundwater Pollution by Nitrogen Compounds in Israel
173
laboratory tests for organic nitrogen and carbon, nitrate, ammonia, pH, chlorides,
electrical conductivity and humidity. The location of groups of drillings and the sampling
were selected in such a way that the results would as far as possible give the effect of only
one main parameter. The most important types of sites of drillings are summed up in
Table 2.
Table 2. Types of sites of drillings for soil tests
Agricultural
use
Type of
soil
Remarks
Flowers under glass
Citrus
Extensive crops
Uncultivated
Citrus
Field crops
Citrus
Field crops
Coarse textured
Intensive fertilization and
irrigation
Coarse textured
Medium fertilization and irrigation
Coarse textured
Minimum fertilization and irrigation
Coarse textured
No fertilization or irrigation
Coarse textured
Application of organic manure; no
chemical fertilization
Coarse textured
Irrigated with wastewater
Fine textured
Medium fertilization and irrigation
Fine textured
Minimum fertilization and irrigation
The main findings are given in Figs. 1-4 and showed:(i) A comparison of the distribution of nitrogen compounds in the soil profile of
cultivated and of uncultivated land showed that as a result of fertilization and irrigation,
nitrates are leached to below the root zone. It seems that leaching of nitrates is a
relatively fast process.
(ii) Contrary to expectation, relatively high ammonia concentrations were found in the
soil profile.
(iii) Relatively high concentrations of organic nitrogen and carbon were found in the soil
profile. In its decomposition, the organic nitrogen represents a potential source of
nitrates.
(iv) No significant differences were observed between concentrations of nitrogen
compounds in soil profiles in citrus plantations of different age (between six and forty
years).
(v) The soil profile composition affects nitrogen distribution: a higher level of nitrate
concentration is found in sandy profiles, and a higher concentration of ammonia — in
clayey profiles.
(vi) The leaching of nitrates in high concentrations was found also on land which
received only applications of organic manure without any chemical fertilization.
COLLECTION AND PROCESSING OF DATA ON GROUNDWATER POLLUTIONS
General
Groundwater pollution by nitrogen compounds is a complex process, affected by
chemical, biological and physical processes such as oxidation of ammonia into nitrates,
denitrification processes, adsorption and fixation processes, mineralization of organic
nitrogen and movement in a non-saturated layer. The fact that the process of
173
laboratory tests for organic nitrogen and carbon, nitrate, ammonia, pH, chlorides,
electrical conductivity and humidity. The location of groups of drillings and the sampling
were selected in such a way that the results would as far as possible give the effect of only
one main parameter. The most important types of sites of drillings are summed up in
Table 2.
Table 2. Types of sites of drillings for soil tests
Agricultural
use
Type of
soil
Remarks
Flowers under glass
Citrus
Extensive crops
Uncultivated
Citrus
Field crops
Citrus
Field crops
Coarse textured
Intensive fertilization and
irrigation
Coarse textured
Medium fertilization and irrigation
Coarse textured
Minimum fertilization and irrigation
Coarse textured
No fertilization or irrigation
Coarse textured
Application of organic manure; no
chemical fertilization
Coarse textured
Irrigated with wastewater
Fine textured
Medium fertilization and irrigation
Fine textured
Minimum fertilization and irrigation
The main findings are given in Figs. 1-4 and showed:(i) A comparison of the distribution of nitrogen compounds in the soil profile of
cultivated and of uncultivated land showed that as a result of fertilization and irrigation,
nitrates are leached to below the root zone. It seems that leaching of nitrates is a
relatively fast process.
(ii) Contrary to expectation, relatively high ammonia concentrations were found in the
soil profile.
(iii) Relatively high concentrations of organic nitrogen and carbon were found in the soil
profile. In its decomposition, the organic nitrogen represents a potential source of
nitrates.
(iv) No significant differences were observed between concentrations of nitrogen
compounds in soil profiles in citrus plantations of different age (between six and forty
years).
(v) The soil profile composition affects nitrogen distribution: a higher level of nitrate
concentration is found in sandy profiles, and a higher concentration of ammonia — in
clayey profiles.
(vi) The leaching of nitrates in high concentrations was found also on land which
received only applications of organic manure without any chemical fertilization.
COLLECTION AND PROCESSING OF DATA ON GROUNDWATER POLLUTIONS
General
Groundwater pollution by nitrogen compounds is a complex process, affected by
chemical, biological and physical processes such as oxidation of ammonia into nitrates,
denitrification processes, adsorption and fixation processes, mineralization of organic
nitrogen and movement in a non-saturated layer. The fact that the process of