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Salado, Lucelle Kate T.
Research Work: Optimum levels of macronutrients (K, Na, Ca, and Mg) for various crops (cacao, coconut, coffee, corn, vegetables).
A fertile soil is essential to obtain the best growth and productivity of various crops. Plants require seventeen essential elements for growth. The essential elements which plants need in relatively small amounts are called micronutrients. Moreover, the elements which plants require in relatively large amounts are called macronutrients. The nutrients such as sodium (Na), silicon (Si), vanadium (V), cobalt (Co), and titanium (Ti) have shown beneficial effects on some plants, but to date have not been accepted as essential for all plants (Bryson & Mills, 2014).
Potassium Potassium is important for transporting carbon from one portion of the plant to another. This nutrient is very important to obtain the desired color intensity of the plant foliage. Plants with critically low potassium levels result in wilting and rapid post harvest decline. Also, the ammonium ion competes directly with the potassium ion uptake, therefore making excess ammonium detrimental to adequate the potassium uptake of the plants (Bryson & Mills, 2014).
Calcium When calcium reaches the leaves, it cannot be moved to a new location within the plant. Since calcium is immobile in the plant, a constant supply of calcium must be maintained for crops that are constantly producing new plant material or new vegetative growth. Calcium moves to the plant root and into the different plant parts through the transpiration stream, therefore any factor that creates a water stress or disrupts the transpiration flow of water will affect the calcium uptake within the plant. Moreover, calcium uptake is also depressed by competitive uptake of ammonium and potassium, therefore, calcium deficiency can occur in soils that are highly fertilized with potassium or ammonium fertilizers (Bryson & Mills, 2014).
In reality, plants can differ in growth rate, root distribution, phase of development, and efficiency of nutrient uptake and utilization that explains why each plant has a specific sufficiency range that is associated with the growth stage of the plant. According to the Plant Analysis Handbook IV by Bryson and Mills (2014), the sufficiency range data of each plant that was given in the handbook has been established by research that contains the concentration range for specific plant part and growth stage within which the optimum plant growth and product yield is obtained.
1. Optimum levels of macronutrients for coconut. Potassium > 0.5 meq
Calcium > 15 meq Source: PNS/BAFS (2018)
2. Sufficiency range for cacao Potassium 1.30 - 2.20 %
Calcium 0.30 - 0.60 % Source: (Bryson & Mills, 2014)
3. Nutrient sufficiency ranges for bananas during its different stages. 6-9 months into production season
At harvest stage
Potassium 3.80 - 5.00 % 2.30 - 4.00 %
Calcium 0.80 - 1.50 % 0.70 - 1.40 % Source: (Bryson & Mills, 2014)
4. Sufficiency range for various coffee plants. A. Coffee arabian or common collected from mature plants. Potassium 2.00 - 2.50 %
Calcium 1.00 - 2.50 % Source: (Bryson & Mills, 2014)
5. Vegetables
A. Common Cabbage 2-6 weeks 2-3 months Head ยพ mature Mature
Potassium 3.50 - 6.00 % 3.00 - 5.00 % 2.00 - 4.00 % 3.00 - 5.50 %
Calcium 3.00 - 4.50 % 1.10 - 3.00 % 1.30 - 3.50 % 1.00 - 2.00 % Source: (Bryson & Mills, 2014)
B. Carrot Middle of the growing season
Mature Plants
Potassium 2.50 - 4.30 % 2.90 - 3.5 %
Calcium 1.40 - 3.00 % 1.00 - 2.00 % Source: (Bryson & Mills, 2014)
โ For Coconut , the range is greater than 100 ppm. Your level is also higher than this minimum. โ For Coffee , the range is 50-200 ppm. Your level is within this range. โ For Vegetables , the range is 45-255 ppm. Your level is also within this range. โ What this means: If you are growing cacao , the manganese level in your soil is extremely high. This could be very harmful to your cacao plants and significantly reduce your yield. For coconut , the level seems sufficient. For coffee and vegetables , the manganese level looks good. โ Manganese toxicity symptoms vary with plant species and among plant tissue organs. On older leaves, manganese appears on plant leaves as brown spots with surrounding chlorotic tissue. Leaf marginal chlorosis and necrosis (e.g., alfalfa, rape, kale, lettuce), leaf puckering (e.g., snap bean, soybean, and cotton), chlorosis and necrotic spots of young leaves (e.g., barley, lettuce, soybean), and interveinal chlorosis of upper leaves (e.g., bean, eggplant, pepper, tomato, and spinach) are commonly occurring symptoms for these crop species. Other physiological disorders attributable to manganese toxicity are crinkle leaf of cotton and bean (associated with manganese-induced calcium deficiency), stem streak necrosis in potato, internal bark necrosis of apple trees, and growth retardation and leaf tip burn of carnation, and blossom-end fruit cracking of muskmelon. A physiological disease known as measles is seen as black specks of manganese oxide in the surface of leaf tissues and fruits. Manganese toxicity metabolic effects include auxin destruction and deficiency due to increased activity of IAA oxidase. This action reduces cell wall expansion and the development of binding sites for Ca+2 transport. Decreased auxin levels, along with death ofterminal buds, may account for the loss of apical dominance and the resulting shoot proliferation (sometimes called "witch's broom") in plants exhibiting manganese toxicity symptoms.
Copper (Cu):
โ Your soil has 177.7 mg/kg of Copper.
โ Acceptable ranges:
โ For Cacao , the range is 0.4-1.8 ppm. Your level is significantly higher. โ For Coconut , the range is greater than 4 ppm. Your level is also much higher. โ For Coffee , the range is 10-40 ppm. Your level is within this range. โ For Vegetables , the range is 6-30 ppm. Your level is also within this range. โ What this means: If you are growing cacao , the copper level in your soil is much too high. This could also be damaging to your cacao plants. For coconut , the level seems good. For coffee and vegetables , the copper level appears to be in a good range.
In Summary:
This soil test suggests that if you are growing cacao , you might have too much Iron, a dangerously high level of Manganese, and too much Copper in your soil. These high levels could be the reason if your cacao plants are not growing well or if your harvest is poor.
For those of you growing coconut , the levels of these three micronutrients seem to be adequate.
For those growing coffee and vegetables , the levels generally look good, but the Iron level for coffee might be something to keep an eye on.
