1. Soil
   The lettuce suffers from chloration when the pH is high, and therefore, a pH of 7 is preferable or acid soil. In winter, light soil is preferable, however good results may also be obtained in heavy soils.

2. Water
   Irrigate every 1-3 days. During hot weather it is preferable to pulse irrigate in order to preserve high humidity. Lettuce suffering from excess water causes rot at the base of the root. The best results were obtained when at the height of the season, the irrigation factor was 1.2, however the biggest heads were acquired when when the factor was 0.8.
   The total amount of water depends on the type of soil. In a light soil where there is no danger of stagnant water, it is possible to work with the higher factor and to attain a better crop.

3. Fertilization
   The amount of nitrogen should not be too high since it can damage the quality. The highest yields were obtained with an amount of 250Kg nitrogen per hectare.
   The recommended method is by fertilizing through the water. Nitrogen 80 - 100 ppm, Potassium 30-35ppm, Phosphorous 140ppm.

4. Distances
   Beds measuring 1.8 m, 4 rows per bed, 30 cm between rows, 30 cm between plants in the row.

5. Density
   80,000 - 120,000 plants per hectare.
   Sowing and thinning is preferable to planting.

6. Growing Seasons
   Two main seasons for sowing, September-October, January-March.
   Harvesting in early varieties is after 6-7 weeks, in late-ripening varieties after 10 weeks.

3. Netafim's Recommendations

1. One lateral for every pair. 0.5 m between the drippers. 0.3 m in light soils. Any type of equipment is suitable.

2. Frequent irrigation cycles on hot days, several times a day in heavy soils and in light soils, every 1-2 days.

4. Results attained with drip irrigation

1. Besor region - light soil

   Growing period 9-10 weeks, density 88,000 plants per hectare.
   The harvest suitable for export was 45 tons per hectare.

2. Jordan Valley - heavy soil
   
   

   Treatments	2Kg Nitrogen daily	3Kg Nitrogen daily	3Kg Nitrogen + 2Kg Potassium
   Irrigation every 2 days	Head weight 523g	568	608
   Irrigation every 3 days	Head weight 601g	-	-
   % heads for export	70%	68.4%	55.6%
   Brown heads - not marketable	6%	5.6%	8.1%
   General harvest	46.02 T/hectare	49.98 T/hectare	53.5 T/hectare
   Export harvest	32.2 T/hectare	33.9 T/Hectare	29.7 T/hectare

   
   

   Experience has shown that late harvesting is the cause of a size not suited to export, and also the administration of excessive quantities of Nitrogen fertilizer should be avoided. Also, application of potassium and phosphorous to the heads increases the browning and yields fewer heads for export. In general, excessive fertilization is found to be detrimental at high temperatures.

5. Economical Data

1. Annual expense for the drip irrigation system is $800 per hectare.

2. At an average price of $300 per ton, a difference of 3 tons pays for the system. An increase of the yield of 5% pays for the system.

3. It should be taken into account that large heads are not necessary. The best head size is 500g at a -density of 120,000 plants. Using correct irrigation, it is possible to achieve 60 tons per hectare. The advantage of drip irrigation is the feasibility of planting large densities and achieving a completely uniform sized head.