1: Nitrogen optimization in Rice

Nitrogen in the plant is a very important subject. Nitrogen plays an important part in many essential functions and compounds necessary for plant life and growth. Nitrogen may be found in various parts of the plant in different forms. There is nitrogen in the leaves, grain, plant tissue and roots of plants. Nitrogen may function as part of the plant structure or be involved in the life processes.

• Nitrogen makes up part of the chlorophyll in plants. Chlorophyll is the green part of leaves and stems. Light energy is taken by the chlorophyll and used to make sugars for the plant.

• Nitrogen is an important part of the compounds that regulate plant growth and development. Nitrogen is also an important part of the plant structure.

• Nitrogen is used to make protein by the plants. Protein is stored in the grain, fruit and seeds of plants.

• In the roots, nitrogen is found in proteins and enzymes. They help the nutrients and water be taken up into the plant.

Why excess nitrogen in agriculture is a problemImpact of nitrogen deficiency:

Plants that are deficient in nitrogen have stunted growth, depending on the severity of the deficiency. Leaf growth is inhibited; younger leaves are inhibited in particular. Longitudinal shoot growth is inhibited, as is the increase in thickness. Deficient plants often become pale green to yellowish-green due to inhibited chloroplast and chlorophyll synthesis. Leaves start to wither and dry out, turning yellowish brown to brown.

Impact of excess nitrogen?

• Excess nitrogen can’t be taken up by plants, thus the excess amount of nitrogen is wasted and farmer’s expenditure increases. Cutting down amount of nitrogen fertilizers can reduce farmer’s input cost, without affecting the yield, increase farmer’s profitability.

• Some soil microorganismcan transform nitrogen provided in fertilizers into nitrogen containing gases. Excess amount of nitrogen (not absorbed by plant) available in the soil will transform into nitrogen containing gases, that get released into the atmosphere like the GHG.

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• 100kg of fertilizer, estimates plant uptake is 80, N balance = +20 

• Target +30kg balance which provides a safe buffer; farmer unlikely to see yield reduction

• There is opportunity to reduce N fertilizer by 20 kg per hectare without impact yieldimpacting the yield

2: Usage and utility of leaf color chart

What is a Leaf Color Chart?

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• Start LCC readings from 14 DAT (Days after Transplantation) or 21 DAS (Days after sowing)

• The last reading is taken when the crop just starts to flower. 

• Randomly select at least 10 disease-free rice plants or hills in a field with uniform plant population from different areas of the plot.

• Select the topmost fully expanded leaf from each hill or plant

• Place the middle part of the leaf on a chart and compare the leaf color with LCC shades

• Do not detach or destroy the leaf

• Measure the leaf color under the shade of your body, because direct sunlight affects leaf color readings  

• If possible, the same person should take LCC readings at the same time of the day every time

• If more than five leaves read below a set critical value, apply

  • 23 kg N ha^-1 (one 50-kg bag of urea/ha) for wet season or 

• The suggested critical values are:

  • 4 for transplanted rice (TPR)

  • 3 for high-density wet-seeded rice (WSR)

• Repeat the process at 7 to 10 day intervals or at critical growth stages (early tillering, active tillering, panicle initiation, and first flowering) and apply N as needed.

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LCC is a guide for application of fertilizer N to maintain an optimal leaf N content. It helps farmers to apply optimum amount of Nitrogen fertilizers, resulting in lesser wastage, lesser input cost with sustainable yield of paddy. 

3: Early transplantation of paddy

Introduction:

Rice crops can be either direct seeded or transplanted. In direct seeding, seeds are sown directly in the field. While in transplanting, seedlings are first raised in seedbeds before they are planted in the field.

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• The ideal transplanting date for paddy is between June 15 to July 15 to get the optimum yield possible

• Proper and timely nursery is important for timely transplantation of paddy

• Nursery timing: 2 weeks prior to the planned date of transplantation

• The delayed nursery transplanted seedlings produce low and weak tillering reducing final yield.

4: Nursery raising

Why Nursery is important?

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