Application of Macro and Micronutrients, Increases Purple Yam Yield
Ube also contains a special type of protein that has an anti-hypertensive property, according to a study conducted by the biotechnology team of PhilRootcrops. This discovery adds value to ube, making it a potential medicine for hypertension and other immune-related diseases like diabetes.
With the crop’s medicinal value and market potential, purple yam production should be given much attention, but the opposite is happening in the Philippines. Here, yams are usually cultivated in highly weathered tropical soils, which have low nutrient reserves, strong acidity, and high amounts of exchangeable aluminum (Al) that are toxic to many crops. Hence, the national average yield value from yam is 5 tons per hectare (ha), which is very low considering the high production cost of yam.
One of the major constraints in yam production in the Philippines is the lack of planting materials because the harvested tubers are used as planting materials for the next cropping. Farmers also usually get very low yields because they apply a very limited amount of fertilizers since yam could grow in many types of soil, according to a survey that the extension team of PhilRootcrops conducted recently.
What many farmers don’t know is that like other crops, yam needs 13 essential elements aside from oxygen, hydrogen, and carbon in order to grow properly. It needs macronutrients such as nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S), and micronutrients such as boron (B), chlorine (Cl), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo) and zinc (Zn) to attain optimum development.
Considering the important role of mineral nutrition on the growth and development of the crop, it is important to supply the soil with sufficient nutrients. But so far, the standard amount of fertilizers that should be applied to yam for it to yield at least 10 tons/ha is not yet established.
This matter inspired this writer to conduct a research to assess the effects of the addition of different levels of micronutrient fertilizers to NPK fertilizers on the growth, yield, tuber quality, and economic returns of purple yam.
The study was conducted at PhilRootcrops in Visayas State University in Baybay City, Leyte. Seven sets of experiments were conducted from 2002 to 2007, and different fertilizer treatments representing six levels of inputs were employed. One hundred grams of tuber setts (VU-2 variety) were used as planting materials, and these were planted at a distance of lm x 0.5 m and at a depth of 10cm.
This writer found out that when 150 kg nitrogen, 50 kg of P205 150 kg of K2O, and 16kg/ha of Biozome-200 micronutrient soil conditioner was applied, purple yam plants became taller and had bigger leaves.
The yield also increased in the first cropping by 163 percent or 18.52 tons/ ha. If this would be based on the national average yield value of 5 tons/ha, it would be equivalent to 370 percent yield increase or P 185,000 net income per cropping. In the second year, the net income increased to about P258,000 per cropping.
This writer also compared the yam tubers that were applied with macro and micronutrients to the tubers that were not applied with, and found out that the purple yams that were applied with macro and micronutrients have higher amounts of magnesium, calcium, sodium, iron, copper, and zinc. The plants are also resistant to anthracnose because they contain manganese, molybdenum, and zinc, which provide resistance to biotic and abiotic stresses.
