Fertilizer: More Harm than Good?
Task 7: Fertilizing is one strategy to manage oil palm plantations. Imagine you work on an oil palm plantation. A new colleague says he has heard that synthetic fertilizers have environmental disadvantages. He asks what you know about possible advantages and disadvantages. List what you know in the table below.
Oil palm management strategy 1: Synthetic Fertilizing
Beneficial Elements for Oil Palm Growth
Task 8: Based on your pre-knowledge, mark the elements which could be essential (green box) and beneficial (orange box) for oil palm growth in the periodic table.
To mark an element, click on it once to turn the box green, click again to turn it orange, and click again to reset the color.
Task 9: Based on your pre-knowledge and your markings in the periodic table, fill in the table below. Don't worry - you can add this later on, if you don't know much yet.
Fertilizer: Nutrients for Feeding our Food
Task 10: Read the text “Nutrients for Feeding our Food”. Add what you learn in this text to your previous answers on task 7, 8, and 9.
Nutrients for Feeding our Food
Substances which plants use to grow are called plant nutrition substances. Plants take these nutrients from the soil through their roots and from the atmosphere through their green parts (e.g., leaves). Few soils are ideal for plant growth by nature and do not supply nutrients in adequate amounts for high yields [22]. The process of adding nutrients to soil is called fertilisation. Thereby, the quality of the soil as well as the quality and quantity of agricultural products can be increased.
The substances which contain nutritional elements are called fertilizer [23]. In varying proportions, fertilizer typically provides three main macronutrients:
for leaf growth
P
for development of roots, flowers, seeds, and fruit
for stem growth, movement of water in plants, and the promotion of flowering
Also, other macronutrients such as calcium (Ca), magnesium (Mg) and sulphur (S) are added to most fertilizer. To fertilize oil palm, micronutrients such as copper (Cu), zinc (Zn) or boron (B) are added to meet the specific needs of the plant [24].
Forms of Fertilizer
The most common multi-nutrient fertilizer for industrial purposes is the three-component NPK fertilizer (containing chemically produced nitrogen, phosphorus and potassium). Also, there is mineral (mined phosphorus and potash) and organic fertilizer. One organic option is stall fertilizer, which is a mixture of animal manure. Manure naturally contains N, P and K, as well as other macro- and micro-nutrients.
Manure increases the amount of organic matter in the soil and the soil's capacity to hold water. This improves the soil's tolerance against droughts and helps soil processing [23].
Within oil palm management, synthetic NPK fertilizer is used. They are often criticized to reduce soil fertility and harm soil microbes when applied in large quantities. On the other hand, one can mix the three components to meet the specific needs of the soil and scatter them accordingly.
Figure 9.1 and 9.2: Mixing and scattering oil palm fertilizer.
Hence, the percentages of N, P and K often vary in multi-nutrient fertilizer, depending on the soils in which they are used. If applied correctly, fertilizer leads to the enhancement of plant growth and increases crop yield. As already mentioned, most soils supply inadequate amounts of nutrients for agricultural purposes. Therefore, not using fertilizer impairs (large- scale) cultivation of crops in general [22]. Moreover, fertilization is needed to feed the world [25]. However, heavy fertilizing can also cause soil and groundwater pollution, as the nutrients get easily washed away by water. The availability of N, P and K in the soil should be sufficient, but not too high. Low availabilities will lead to hampered growth and low yield. Too high availabilities may lead to disturbed plant growth and negative effects on yield. In both cases, the quality of harvested products can be decreased. The conflict of short-term gains vs. long-term losses must be considered when working with synthetic NPK fertilizer.
Nutrients for Oil Palm Health
Additional information: Besides plant growth, nutrients are also important for plant health and yield. Below, there are examples of unhealthy trees with nutrient deficiencies [26].
Supplementary question:
Do you know the same or similar nutrient deficiency symptoms from other plants?
Nitrogen Deviciency
Pale green or yellow-green leaves caused by lack of chlorophyll. Occurs in flooded, waterlogged, and anoxic soils.
Phosphorus Deviciency
Slow growth and leaves become olive-green, brown necrosis occur around edges. Palms are appearing stunted and have a small bunch size with a pyramid-like shaped trunk.
Potassium Deviciency
Confluent orange spotting, marginal necrosis on older leaves. Typical on peatland.
Magnesium Deviciency
Strong and striking orange colour, hence also called Orange Frond. Typical on sandy soils with high rainfall.
Boron Deviciency
Small hook leaves with bent points are corrugated and malformed. Short petioles.
Copper Deviciency
Also known as ‘nursery white stripe’, mainly on younger leaves with chlorosis and necrosis on the tips. Small fruit bunches. Typical on peatland.
Iron Deviciency
Pale chlorosis and necrosis in sand culture. Rare with oil palms growing on acid soils with much iron oxide.
Nitrogen-Potassium Imbalance
Known as white stripe and occurs where the K:N ratio is wide.
Ganoderma Deviciency
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