The soils cultivated under cover deteriorate due to irrigation with saline waters, excessive fertilization, limited drainage and absence of leaching of salts by rain. The objectives of the work were to forecast leaching water depth, recover a salinized soil by hydro improvement method, maintain the tolerable soil salinity by the lettuce crop applying the leaching requirement and evaluate the saline dynamics of the soil cultivated and irrigated with the Balansal model. In a greenhouse drain tubes were buried at 50 cm spaced every 2 m and 0.2 m3 tanks were installed at the discharge. The leaching water depth was predicted using 6 mathematical models and into basins of 10 m2, the initial and residual electrical conductivities of the soil and drained water were measured after applying 3 water depths, totalling 320 mm. The main results were: the predicted leaching water depth averaged 320 mm; the average initial soil salinity of 4.69 dS.m-1 was reduced to 0.81 dS.m-1 after the last leach; the salts decrease of the first leaching with respect to the initial salinity was 74.1%, that of the second leaching was 31% and that of the third leaching was 3.7%; the salinity of the drained water was 0.97 dS.m-1; 0.91 dS.m-1 and 0.88 dS.m-1 after each leach, respectively. With the application of a leaching requirement of 15%, the soil salinity was maintained at 0.87 dS.m-1 and the Balansal model predicted with good adjustment the saline dynamics of the soil during the crop cycle.

In June 2011, the eruption of the volcanic complex Puyehue expelled large quantities of ash into the atmosphere that are currently being evaluated for use. The aim of this work was to evaluate the feasibility of using these ashes as substrate component. Physical and chemical analyses were carried out on samples collected from the affected area sand substrates made with Sphagnum peat and ash proportions of 20 and 50 %. Formulated substrates were also evaluated by developing of coral plant (Salvia splendens). The ash samples ranged from pH 5.7 to 7.2; the values of electrical conductivity and concentration of calcium, magnesium, potassium and sodium were low. Physics results showed that bulk density was inverse to the size of particles. Also, to larger particle size was greater the aeration porosity and to smaller sizes was greater the water holding capacity. The substrates formulated were suitable chemical and physical properties. Consequently, the totality of coral plants were quality, but plants of the substrates with 20 % fine ash and 50 % ash mixture, obtained the highest fresh and dry mass. In conclusion, the volcanic ash is a viable material for use as a substrate, but air and water ratio must be balanced according to its particle size.

Accumulation of salts and sodium in the soil for the continued use of poor quality water affects the structural stability, hydraulic conductivity and infiltration rate of the soil, causing a reduction in their productive capacity. In the greenhouse, all water must be provided in the form of irrigation, so it is important to know the water quality to be used. This is defined in terms of salinity, sodicity and toxicity. There are records reporting changes in the chemical properties of soils irrigated with water of questionable quality. According to these, the use of such water brings about changes in physical and chemical properties of soil. The higher the SAR, the lower is the hydraulic conductivity and decrease soil infiltration and surface crust appears damaging the germination and crop emergence. Lettuce is moderately resistant to salinity, although in greenhouses, the development of the crop can be affected by the increase in soluble salts. Saline-sodic soils can be restored using chemicals amendments. These counteract the increased levels of sodium and stabilize the soil structure.

Rosario Horticultural Belt exhibits soil degradation and a decline in crop productivity. A trial was conducted in Facultad de Ciencias Agrarias UNR, Zavalla, Santa Fe, to assess the effect of different organic amendments and N-fertilizer on soil properties and productivity of broccoli and lettuce. In 2001-2002, vermicompost of household waste; vermicompost of rabbit and horse manure; chicken manure were incorporated at doses of 1 and 2 kg·m-2 dry basis, and at a dose of 2 kg·m-2 in combination with urea (46 % N) during 2003-2005, and a control was performed. Organic carbon, saturated flow hydraulic conductivity, pH, electrical conductivity, and structural stability were evaluated in soil. Broccoli yield, inflorescence average weight, inflorescence diameter, and lettuce yield and average weight of plant were measured. Soil organic carbon, aggregate stability and electrical conductivity increased, and there were significant differences in broccoli yield and average weight, as a result of amendment addition at the highest dose. In lettuce, differences were found for the highest dose in the first phase of the experience. Chicken manure showed differences in yield and average weight in the first two cycles for lettuce and in the two cycles for broccoli in the second phase. The fertilized plots showed differences in yield and average weight for both crops, in 2004 and 2005. The effect of the amendments on the productivity was higher during the first years, while fertilization influenced in the last years of the experiment. The organic amendments significantly improved soil conditions. The nitrogen fertilization increased productivity in both lettuce and broccoli.