Monitoring of Electrical Conductivity and pH in Soil Solution At Fertigated Citrus Trees.

The citrus industry is a segment of great importance to Brazil, which is the world largest producer of orange. Fertigation is a technique that is increasingly expanding in the citriculture, but this technique is usually performed using predetermined doses without monitoring the nutritional status of plant and soil. The mismanagement of fertigation can cause imbalances in soil conditions and plant nutritional status over time. Traditional techniques for monitoring the condition of the soil does not allow the provision of data quickly, wasting this great potential of fertigation. This research aimed to evaluate the effect of five N and K rates on the electrical conductivity and pH at soil solution, thereby observing the sensitivity of these methods. The experiment occurred out in the city of Reginópolis-SP/Brasil, using ‘Hamlin’ trees, grafted on citrumelo Swingle rootstock. The treatments consisted of five N and K rates, applied through fertigation: T1 - control (no nutrient), T2 - 25%, T3 - 50%, T4 - 100% and T5 - 200% of N and K. The 100% rate, officially recommended, was established based on historical of soil and leaf analysis and also in accordance with the expected productivity. The remaining rates was calculated from it. The soil solution analyses were made with the help of porous covering soil solution extractors. There was decrease in pH and increase in electrical conductivity with increasing rates of N and K applied by fertigation. There was increase in electrical conductivity at 60 cm on the most rainy months, what can indicate a potencial loss of nutrient by leaching.