Unit 6 - Practice Quiz

Phosphorus is immobile in soil and susceptible to fixation by clay minerals and oxides. Band placement minimizes soil-fertilizer contact and places nutrients near the root zone, thereby increasing availability and efficiency.

The STCR (Soil Test Crop Response) approach, pioneered in India by Ramamoorthy, uses specific equations to calculate fertilizer doses required to achieve a specific yield target based on soil test values.

The Leaf Color Chart (LCC) is a simple, low-cost tool used to measure the greenness of rice leaves, which correlates with plant Nitrogen status, helping farmers decide when to apply N fertilizer.

IPNS aims to maintain soil fertility and plant nutrient supply at an optimum level for sustaining desired crop productivity through optimization of the benefits from all possible sources of organic, inorganic, and biological components in an integrated manner.

Agronomic Efficiency (AE) represents the quantity of yield increase per unit of nutrient applied. It is calculated as (Yield in fertilized plot - Yield in control plot) / Amount of nutrient applied.

In rain-fed agriculture, adequate soil moisture is essential for the dissolution of fertilizers and the transport of nutrients to plant roots. Lack of moisture severely restricts nutrient uptake and efficiency.

Proper nutrient management increases crop growth and biomass. When roots and residues (biomass) are returned to the soil, they add organic matter, leading to increased Soil Organic Carbon (SOC) sequestration.

Urea hydrolyzes to form ammonium carbonate, which is unstable. In alkaline conditions or surface application without incorporation, it rapidly converts to ammonia gas (), leading to significant volatilization losses.

In the STCR targeted yield equations, NR stands for Nutrient Requirement, which is the specific amount of nutrient (N, P, or K) required to produce a unit quantity (e.g., 1 quintal or tonne) of grain yield.

Fertigation is the application of water-soluble fertilizers, soil amendments, or other water-soluble products through an irrigation system.

A SPAD meter (Soil Plant Analysis Development) provides a reading that correlates with the chlorophyll content of the leaf, which is directly related to the Nitrogen status of the plant.

In carbon trading, one carbon credit represents the right to emit, or the sequestration of, one metric tonne of carbon dioxide or its equivalent in other greenhouse gases.

Deep placement of Urea Super Granules (USG) in the reduced zone of flooded rice soils minimizes ammonia volatilization and denitrification losses, thereby significantly improving NUE compared to surface broadcasting.

Justus von Liebig proposed the Law of the Minimum, stating that plant growth is limited not by total resources available, but by the scarcest resource (limiting factor).

Neem oil coating on urea acts as a nitrification inhibitor. It slows down the activity of nitrifying bacteria, keeping nitrogen in the ammonium form longer and reducing losses via leaching (as nitrate) and denitrification.

Partial Factor Productivity (PFP) is a simple ratio of total yield produced per unit of fertilizer applied. It answers the question: 'How much crop is produced for every kg of fertilizer used?'

In STCR equations, %CS stands for Percent Contribution from Soil, which is the percentage of available soil nutrients (measured by soil test) that the crop utilizes.

GreenSeeker is an active optical sensor that measures plant biomass and vigor using NDVI (Normalized Difference Vegetation Index) to determine real-time nitrogen requirements.

Foliar spray is the most effective method for correcting acute micronutrient deficiencies quickly because nutrients are absorbed directly through the leaves, bypassing soil fixation issues common with metals like Zn and Fe.

The Critical Limit (or Critical Level) is the concentration of a nutrient in the soil (or plant) below which the plant will experience deficiency and respond significantly to added fertilizer.

Rhizobium is a biofertilizer containing live bacteria that fix atmospheric nitrogen in the root nodules of leguminous plants.

In irrigated soils, particularly coarse-textured ones, nitrate () is highly mobile and easily washed down below the root zone with percolating water. This process is called Leaching.

The C:N ratio controls decomposition. A high C:N ratio (>30:1) leads to N immobilization (microbes consume soil N), while a low C:N ratio (<20:1) promotes N mineralization (release of N).

Top dressing refers to the broadcasting or application of fertilizers (usually Nitrogen) on the soil surface in a standing crop to meet nutrient demand during active growth stages.

Pop-up fertilization involves placing a small amount of fertilizer in direct contact with or very close to the seed to stimulate early growth and establishment, acting like a 'starter'.

Increasing SOC sequesters carbon that would otherwise be in the atmosphere as (a greenhouse gas), thus helping to mitigate climate change.

%CF stands for Percent Contribution from Fertilizer. It represents the efficiency with which the crop utilizes the nutrients applied through fertilizer.

Zero tillage or conservation tillage minimizes soil disturbance, reducing the oxidation of soil organic matter and allowing carbon to build up (sequester) in the soil over time.

Phosphorus is highly immobile in soil. It must be applied basally (at planting) and placed in the root zone so that roots can access it as they grow. It cannot effectively move to roots if top-dressed later.

SSNM involves optimizing the supply of soil nutrients over space and time to match crop requirements, accounting for local variations in soil fertility and crop potential.

Potassium regulates stomatal opening and closing. Foliar application of K helps maintain cell turgor and improves the plant's ability to withstand moisture stress (drought tolerance).

Recovery Efficiency (RE) is calculated as: . It measures how much of the applied nutrient the plant actually acquired.

Denitrification is a microbial process that occurs in anaerobic (oxygen-depleted) conditions, such as waterlogged soils, where bacteria use nitrate as an electron acceptor instead of oxygen, releasing or gas.

Farm Yard Manure (FYM) is a bulky organic manure used in IPNS to supply nutrients and, more importantly, to improve soil physical properties and increase organic matter content.

Blanket recommendations are generalized fertilizer doses (e.g., state or regional recommendations) provided for a region, assuming average soil fertility, without considering field-specific soil test values.

Anhydrous ammonia is a gas at ambient pressure. It must be injected deep into the soil and covered immediately to prevent it from vaporizing and escaping into the atmosphere.

Nutrient Expert is a computer-based Decision Support System (DSS) developed (e.g., by IPNI) to generate Site-Specific Nutrient Management (SSNM) recommendations for farmers.

Weeds compete with crops for nutrients, water, and light. High weed infestation results in the weeds consuming the applied fertilizer, thereby significantly decreasing the NUE of the crop.

Split application provides Nitrogen at critical growth stages when the plant needs it most. This reduces the time Nitrogen sits in the soil unabsorbed, thereby reducing leaching and volatilization losses and increasing efficiency.

The Build-up and Maintenance approach aims to apply fertilizer to build soil test levels to a critical value (Build-up) and then apply enough to replace what the crop removes (Maintenance) to keep it there.

is a stable isotope of Nitrogen used as a tracer in agricultural research to precisely determine how much of the applied fertilizer nitrogen is taken up by the plant versus retained in soil or lost.

Cap and Trade is a market-based approach where a limit (cap) is placed on emissions. Companies below the limit can sell (trade) their excess allowances or credits to those exceeding the limit.

While easy, broadcasting urea on the surface results in high exposure to air and sunlight, leading to rapid hydrolysis and loss of ammonia gas (volatilization), resulting in low nutrient use efficiency.

Legumes form a symbiotic relationship with Rhizobium bacteria to fix atmospheric nitrogen. Including them in rotation (IPNS) adds biological nitrogen to the soil, reducing the need for synthetic N fertilizers for subsequent crops.

DRIS uses nutrient ratios (e.g., N/P, P/K) in plant tissue analysis rather than absolute concentrations to diagnose nutrient imbalances and rank the order in which nutrients are limiting yield.

Slow-Release or Controlled-Release Fertilizers (e.g., polymer-coated urea) are designed to release nutrients gradually, synchronizing supply with plant demand and reducing losses, thereby improving NUE.

A low LCC reading indicates leaf paleness due to Nitrogen deficiency. If the reading is below the critical threshold, immediate Nitrogen application is required to maintain yield potential.

Potassium fixation occurs when ions are trapped between the layers of 2:1 clay minerals like Vermiculite and Illite. The type of clay is the primary determinant of fixation capacity.

Under mechanisms like the Clean Development Mechanism (CDM), emission-reduction projects in developing countries earn Certified Emission Reduction (CER) credits, which can be traded and sold.

Hidden hunger refers to a state where the plant is deficient in a nutrient, causing a reduction in yield or quality, but the deficiency is not severe enough to cause visible morphological symptoms (chlorosis, necrosis).