Lecture 3 - Nutrient Management for Agricultural Sustainability Glossary

Chlorosis

yellowing of leaves due to nutrient deficiency

Critical K Level

soil K levels at which 95% of crop yield achieved

DEFRA RB209

crop nutrition guidance, issued by UK Dept. for Environment, Food & Rural Affairs

Denitrification

bacterial reduction of Nitrite (NO2-) & Nitrate (NO3-) to NO, N2O & Nitrogen gas (N2)

Dissolution Rate

rate at which plant available nutrient (K+) liberated from unavailable source (rock)

FYM

Farmyard manure = Organic fertiliser

Ion exchange capacity

ability of the soil to bind charged particles (ions)

Liming

adding basic materials (e.g. agricultural lime, CaCO3) to alkalise the soil

Leaching

infiltration of nutrients below the crop rootzone

Nitrification

aerobic chemical process converting Ammonia (NH3) to Nitrite (NO2-) to Nitrate (NO3-)

Reflectance

light reflected by a leaf )determined by its chlorophyll content)

Offtake

removal of nutrient with crop harvest

Urea

cheapest form of N fertiliser = 46.6% N

Volatilisation

gaseous losses (of NH3) from soil due to urea application or manure.