Can you better explain your question? Do you mean: fertilization causes salinity and how can we reduce this effect? Or: How can we manage fertilization to reduce an existing salinity problem of the soil? Or what?

I mean that under salinity, the farmer has to chose the right source of nutrient, the right quantity, the right time of application and the right method of application. The aim is reducing the effect of the existing soil salinity.

When it comes to foliar fertilisation would propose to switch from water soluble salt to non-soluble minerals.

e.g. from CaCl2 to CaCO3; ZnSO4 to ZnO. They can be formulated as water or oil suspension. They can also be formulated in the submicron range for improved efficiency.

AS i know, chemical fertilizers increase the field salinity. For decrease the field salinity we can use organic fertilizers such as the green manure and vermicompost.

The generally accepted fertilizer is farmyard manure (FYM) for agriculture in most saline areas. The joint application of FYM and chemical fertilizer is recommended when the cost/benefit is considered. The timing of topdressing fertilizer is important to reduce the effect of salt stress on crop growth. Fertilization is suggested after the rainfall or irrigation and high-frequency fertilization is also encouraged with little amount of fertilizer every time. In my opition, the most efficient method to reduce salt stress is to inhibit the capillary rise of soil salinity, namely minimizing the evaporation rather than transpiration. Thus, many measures such as plastic film, straw mulching, isolation layer in the plowing layer are preferable, and drip irrigation is also suggested.

Depende del tipo de suelo y el tipo de salinidad, si es por sulfatos, cloruros, etc, asi mismo se deberá manejar la fertilización, reduciendo las aplicaciones de las mismas sales, además en suelos salinos debería procurarse el uso de abonos verdes, hongos formadores de micorrizas arbusculares y PGPR, para así reducir la cantidad de fertilizantes químicos a aplicar.

To improve / neutralized soli salinity due to parent materials exist in the soil, use of acid farming chemical fertilizers like ammonium sulphate(AS) Anhydrous Ammonia, liquid ammonia, apart from one can go for use of bulky organic manures like FYM, Green manures, and growing of crops with adequate foliage and deep root systems. However growing of crop which can resist salinity for initially few crop cycles also boost up the capabilities for mitigating mall effects of salinity. Use of good quality water or conjunctive use of water is highly advocated.

While the question is not very clear, I presume that the questioner is referring to fertilizers that can be applied in saline soils. If that is the case, one should do use fertilizers that would ameliorate the problem and at the same time supplying nutrients to the crop. As already mentioned by others, one should consider usage of manures or compost to improve the soil conditions. Nitrogenous fertilizers will certainly exacerbate the problem. The soil already has ample bases that would have otherwise been supplied through application of basic fertilizers at or before planting. N requirement for such soils should be made available through use of green manure or well decomposed straw or farm yard manure.

Green manure crop like Sun hemp and Danicha cops cultivated in salinity soil. To absorb the salinity from root nodules.

Dear El-Zanti

I think at first you must refer to source of salinity in your soil. If your main source is Na and not Na and Ca, you can add some Ca to improve salt tolerance of crop plants. Also, a cation which may play a greet role in salt tolerance is K. therefore, if you add fertilizer from K resources it may increase plants tolerance to salinity. It is necessary to say some K sources, such as KCl may reduce salt tolerance. In our experiments and according to literature review, K2SO4 may a better source for increasing salt tolerance.

Like to other friends, if costs have not problem, organic fertilizers by reducing soil evaporation and increasing soil capacity for water holding may improve salt tolerance.

At the end spraying micro elements especially B, Fe and Zn may have a role in this area.

Dear El-Zanaty: I worked on this topic on 2001, you can find an abstract of the published work

Influence of N form (NO3− vs. NH4+) and salinity on tomato yield and fruit composition

The interaction of nitrogen form (NO3 −, vs. NH4 +) and salt stress on the yield and quality of tomato (Lycopersicum. esculentum L. cv. Daniella) fruit was investigated. Four combinations of NO3 −, and NH4 + (0%, 10%, 20% and 40% NH4 +) at 10 mM total nitrogen and two salt levels (0 and 40 mM of NaCl) were used for continuous fertigation. Fruit quality was evaluated based on °Brix, EC and the content of cations, anions, carboxylic acid and sugars. The nitrogen form did not affect the content of mineral nutrients (except K+), carbohydrates and pigments of the fruits substantially, indicating that its composition is under strict metabolic control. However, exposure to salt led to higher °Brix values, and increased contents of Na+, K+ and malate2− in the fruit, particularly at low NH4 + supply. NO3 − contents of the fruits were low irrespective of the N regime and salinity. In contrast, the Cl− content (molar basis) of fruits increased substantially upon exposure to salt, which reinforces the importance of Cl− as an inorganic osmoticum in tomato fruits.

Enhanced N or K fertilization increases the threshold salinity value at which yield starts to decrease with the salinity (TOLERANCE) but the rate of field reduction per one unit of salinity – the slope (SENSITIVITY) is also increased, which is dangerous to plantts, if soil salt concentration is very high.

These relations are shown in several articles of the Proceedings of the International Symposium onTechniques to control Salination for Horticultural Production. Aksoy, U.; Anaç, D.; Anaç. S.; Beltrao, J.; Ben Asher, J.; Cuartero, J.; Flowers, T.J.; & Hepaksoy, S. (eds.). 2002.  International Society of Horticultural Science, Leuven, Belgium.

Several specific articles on these relations are:

- Beltrão, J.; Ben Asher, J; & Magnusson, D. 1993.Sweet corn response to combined effects of saline water and nitrogen fertilization. Acta Horticulturae 335:53-58.

 - Beltrão, J.; & Ben Asher, J. 1997. The effect of salinity on corn yield using CERES-Maize model. Irrigation and Drainage Systems 11:15-28.

- Neves, M.A.; Miguel, M.G.; Marques, C.; Panagopoulos, T.; Beltrão, J. 2006. Response of Tetragonia tetragonioides (Pallas) Kuntze to the combined effects of salts and nitrogen. Transactions on Environment and Development 2(4):470-474.

 - Khaydarova, V. 2006; & Beltrão, J. 2006. Response of Lettuce yield to the combined effects of salts, nitrogen and water. WSEAS Transactions on Environment and Development 2(5):512-518.

Nice responses have already come in , though i am bit late . but , i strongly feel , in ordert o reduce the effect of salinity through fertilizers, best course would be to maintain the  bit above optimum soil  moisture to keep salts below rootzone  and extra addition of nutrients like Cu , K, and P ...