Nutrient Management

KEY CHECK 5:
Sufficient nutrients from tillering
to early panicle initiation (EPI) and
flowering

Nutrient inputs as fertilizers fill the gap between what the crop needs and what is currently present in the soil, water, and air. Sufficient nutrients from tillering to EPI and flowering ensure good growth and uniform panicle development of the crop. They also ensure attainment of the crop’s yield potential.

If nutrients are insufficient during these stages, there may be slow growth, less tillers and panicles, fewer seeds, and lighter grain. Excessive nutrients will cause pest damage, lodging, and soil pollution.

ASSESSMENT OF KEY CHECK

No symptoms of nutrient deficiency or toxicity from tillering to early panicle initiation (EPI) and flowering.
Achieved at least 300 panicles/m2 (TPR) or 350 panicles/m2 (DWSR) at dough stage.

How to assess the number of panicles at dough stage:

1. Randomly select three sampling sites (1m x 1m quadrat) at least 1m from the dike and in a diagonal line across the field.
2. Count the panicles in each quadrat and get the average panicles/m2.

assess the number of panicles at dough stage:

RECOMMENDATIONS TO ACHIEVE KEY CHECK

1. Know and manage the nutrient requirements of your crop based on:

a. visual observation of deficiency symptoms

Tips in proper visual diagnosis of nutrient deficiency

Tips in proper visual diagnosis of nutrient deficiency b. results of nutrient diagnostic and decision support tools such as:

leaf color chart

Leaf Color Chart/Computing (LCC) App
Tools to assess the nitrogen status of the rice crop using a 4-colored “ruler” for leaf color comparison, or an ICT-based mobile application that captures digital leaf images.

Moet app

Minus-One-Element Technique (MOET) and MOET App
A soil nutrient diagnostic technology done through a pot experiment complemented with an ICT-based application to
determine the nutrients deficient in the soil and the amount of fertilizer needed to attain a certain
target yield.

Nopt

Nutrient-Omission-Plot Technique (NOPT)
A means to assess indigenous nutrient supply to serve as basis of
fertilizer recommendation.

rcm

Rice Crop Manager (RCM)
An ICT-based platform for rapidly deploying improved nutrient
and rice-farming management technologies.

c. other available information such as data obtained from extension workers or rice specialists

2. Know the right element, amount, and timing of fertilizer application. Make E-A-T right.

E – Know the right nutrient ELEMENT that the plant needs. Giving the right nutrients increases cost efficiency and attainment of target yield.

A – Know the right AMOUNT of fertilizer to apply. Too much or too little is not good.

T – Know the right TIMING of fertilizer application to increase efficiency in input cost and nutrient uptake.

NITROGEN (N)

Right element. N promotes rapid growth for increased:
• plant height, tiller number, and leaf size;
• number of panicles per hill;
• number of spikelets per panicle;
• grain protein content; and,
• percentage of filled spikelets.

N deficiency results in stunted, yellowish plants; older leaves or whole plants are yellowish green.

(Right) N-deficient rice plant.

Excessive N during panicle initiation and flowering:
• makes the plant prone to lodging and pests;
• increases unfilled spikelets;
• is costly and may contribute to environmental pollution.

Right amount. Use results of LCC/LCC App or the recommendations of the, RCM, NOPT, and MOET/ MOET App as basis in properly determining the amount of N to apply.

Right timing. If LCC/LCC App is available:

• use LCC every 7 days from 14 DAT or 21 DAS until early flowering
• apply N if 6 or more out of 10 leaves are below 4 (TPR) or 3.5 (DWSR).

If LCC/LCC App is not available:

	Application
	1st	2nd	3rd
For ≤ 110-day maturity	0-14 DAT or 7-10 DAS	5-7 days before panicle initiation
For > 110-day maturity	0-14DAT or 7-10 DAS	midtillering	5-7 days before or after panicle initiation

PHOSPHORUS (P)

Right element. P functions mainly for energy storage and transfer. In rice, it promotes vigorous root development, tillering, and early flowering and ripening.

Deficiency symptoms include:
• stunted dark green plants with narrow, short, very erect leaves and greatly reduced tillering;
• thin stems and retarded development; and,
• less leaves, panicles, and grains per panicle

Right amount. Use results of MOET/ MOET App or the recommendations of RCM as basis in properly determining the amount of P to apply.

Right timing.

	Application
TPR	0-14 DAT
DWSR	7-10 DAS

POTASSIUM (K)

Right element. K in rice plants:
• speeds up root growth and boosts plant vigor;
• accelerates uptake of other nutrients;
• improves tolerance of rice to adverse conditions such as pest and disease infestations, drought, lodging; and,
• increases grain size and weight, and percent filled grains

K deficiency is often not detected because its symptoms do not appear until the later growth stages, and are not as easy to recognize as those of N deficiency.

K-deficient rice plant.

K deficiency symptoms include dark green plants with yellowish brown leaf margins or dark brown necrotic spots first appearing on the tip of older leaves. Yellowing follows a “Ʌ” pattern and progresses downward if deficiency is not corrected.

Right amount. Use results of MOET/ MOET App and RCM as basis in properly determining the amount of K to apply.

Right timing.

	Application
	1st	2nd
TPR	0-14 DAT	5-7 days before or after panicle initiation
DWSR	7-10 DAS	5-7 days before or after panicle initiation

ZINC (Zn)

Right element. Zn promotes good seedling and overall growth of plants. It is essential for several biochemical pathways and structural processes in the rice plant.

Zn deficiency symptoms include dusty brown spots on upper leaves of stunted plants appearing 2-4 weeks after transplanting. In Zn-deficient soils, NPK fertilizers alone cannot provide good yield unless the deficiency is corrected.

Zn-deficient rice plant.

Right amount and timing. Use results of MOET/MOET App or the recommendations of RCM as basis in properly determining the amount and timing of Zn application.

If MOET/MOET App or RCM are not available, choose only one among the following amelioration techniques:

	AMELIORATION TECHNIQUES	AMOUNT	TIMING
TPR	Seedling dip	2% ZnO solution	dip for 15-30min
	Seedbed	apply 0.5kg ZnSO4 per 400m2 seedbed or 40kg seeds if deficiency is mild; 2kg if severe	seedbed at 7-10 DAS
	Broadcast	25kg ZnSO4/ ha	10-14 DAT
	Foliar spraying	follow product recommendation	14 DAT
DWSR	Seed Zn coating	1kg ZnSO4 per 40kg seeds	soak seeds in ZnSO4 solution during the last change in soaking water before incubation

SULFUR (S)

Right element. S in rice plants:
• promotes uniform growth and maturity;
• speeds up chlorophyll production, protein synthesis, and plant function and structure; and
• reduces yield if deficiency occurs at vegetative stage

Symptoms of S deficiency include yellowing of young leaves, less tillers, fewer and shorter panicles, reduced number of spikelets per panicle, and delayed maturity.

(Left) S-deficient rice plant.

Right amount. Use results of MOET/MOET App or recommendations of RCM as basis in properly determining the amount of S to apply. The amount of S in 14- 14-14-12S (12%S) as recommended to treat P and K deficiencies is adequate to correct usual S deficiency.

Right timing.