Response of Pearl Millet to Fertilization by Mineral Phosphorus, Humic Acid and Mycorrhiza Under Calcareous Soils Conditions

Fertilizers are a costly input but continue to make a significant contribution to the production of additional food. To maximize benefits and minimize nutrient loss from fertilizer, it must be used in the right amount, source and combination at the right time using the suitable method.
The experiment was carried out during the 2018/2019 summer season in Mariout, Desert Research Center Agricultural Experiment Station, southwest of Alexandria, Egypt to study the effect of the inoculation with Mycorrhizal (MF) fungi, Humic Acid (HA) applied to soil at levels (0, 8 and 16 kg fed-1) and phosphorous foliar application as phosphoric acid (H3PO4 72.5% P2O5) at rates of (0, 0.75 and 1.5 ml/ l) on the yield, yield components and chemical composition of pearl millet (Pennisetum galaucum L.).
Results revealed that inoculation of pearl millet by Mycorrhizal fungi, combined with application humic acid (16 kg/fed) and phosphoric acid (1.5ml/l) was the most effective treatment in improving fresh and dry forage yield which recorded (80.9 and 21.3 ton/fed), respectively through the whole season and recorded the highest protein content which was 24.3% for the 3rd cut compared with other cuts. The inoculation of pearl millet by Mycorrhizal fungi, combined with application humic acid (16 kg/fed) was the most effective treatment in improving dry matter and starch 31.1and 23.7% respectively, as the mean for three cuts. Also, this treatment recorded the highest values of nitrogen as concentration and uptake 2.65% and 184.7 kg N/fed as soon as, phosphorus concentration and uptake values 0.46% and 32.9 kg P2O5 /fed respectively, as the mean for three cuts in the dry forage of pearl millet.
Regarding yield, there was an increase in forage yield and nutrient uptake, especially P and N. N and total antioxidants. Increasing rates of humic and phosphoric acid addition with mycorrhizae treatments increased total antioxidant activity (TAA) of leaf. TAA recorded the highest in the H2 and P2 with inoculation about 796, 663 and 425 (µg AAE/mg ext.) in 1st, 2nd and 3rd cuts respectively. These results indicated a marked improvement in the nutrient availability status of calcareous.