Cereals 2024 Week 8 Crop Nutrition Nitrogen Part 1 Handout Flashcards
What sort of crops need high P requriements?
crops will differ in their nutrient
requirements e.g. high P requirement for
root crops
Nitrogen and Grain Yield in Cereals
1-The total amount of N taken up by a cereal crop
is closely related to what?
2- Whats the key parameter?
3- the total crop N uptake can be divided into what?
1- Grain Yield
2-the total crop N uptake can be divided into soil
N and fertiliser N components
Nitrogen and Grain Yield in Cereals
- the relative contributions of soil N and fertiliser
N are stable or variable?
1- Variable
varying with field history and seasonal factors
– hence yield response curves to fert. N will vary
with site and season
Fertiliser N Response Curve and Season
The effect of tillage system on the grain yield response to nitrogen for winter wheat
at Teagasc Oakpark over three years 2009-2011
Year 1
Year 2
Year 3
RT = reduced tillage CT = conventional tillage
Year 1- RT , CT- Same level 8.5
Year 2- RT- Grain yield- 5,
CT- Grain Yield- 8
Year 3- RT- Grain yield- 9.5
CT- Grain Yield- 9
Why are high crop nitrogen uptake levels
required for high grain yields ? (3)
1* adequate crop canopies - ( leaf area index )
– there is a direct linear relationship between
nitrogen uptake and leaf production
2* long leaf area duration - high leaf N% delays
leaf senescence
3* high yield components - crop nitrogen uptake is
linearly related to grain numbers/m2
W. Wheat
?kgN/ha
S. Barley
?kgN/ha
250
150
N in the soil – N mineralisation:
1- Nitrogen can become available through what?
2- What % of the nitrogen cycle is between plants, micro-
organisms and the soil?
3- Nitrogen in the soil becomes available by
what?
4- The rate of soil nitrogen mineralisation is affected by
many factors, some of the most important are below:
1- Nitrogen can become available through the nitrogen
cycle
2- 95% of the nitrogen cycle is between plants, micro-
organisms and the soil
3- Nitrogen in the soil becomes available by
mineralisation, when organic nitrogen is turned to
inorganic nitrogen
4-
– soil organic matter content
– Soil temperature
– Soil moisture
Crop nitrogen uptake over the season for a winter cereal crop
Soil N uptake increases earlier (from October onwards)
But
Fertiliser Nitrogen Uptake starts on march and increases significantly into august
Total Nitrogen Uptake massively increases from march to august
slide 14 and 18
What sort of importance does N have in role in crop growth
N has a practically important role in crop growth e.g. Tillering
very important for cereal crop density and structure
excellent crop structure and crop growth
Nitrogen nutrition and grain yield in
winter wheat, what’s a key parameter?
- What is is measured as?
What % of above-ground nitrogen is in the grain
Key parameter : Crop Nitrogen Uptake (kg/ha)
measured as the total nitrogen present in the above
ground crop parts at harvest
grain nitrogen + straw nitrogen
– ~ 70% of above ground nitrogen is in the grain
Nitrogen Nutrition of Cereal Crops
1- What is the standard practice with nitrogen?
2- Use of organic N what is this primary?
1* Use of fertiliser nitrogen
– Standard practice with 2-3 applications of
chemical N per season with rates of 100-230 kg
N/ha/season
– Dramatic increase in cost since 2007
2* Use of organic nitrogen
– Primarily the application of animal waste
products, also other organic N sources
Slide 31 and 32 soil type
Role of Soil nitrogen tests in Crop Production
1- In order to apply nitrogen accurately to a crop the amount
of nitrogen what needs to be known?
2- What has reserch worldwide tried to develop?
3- What have some researchers successfully developed?
4- What are some also?
1* In order to apply nitrogen accurately to a crop the amount
of nitrogen the soil supplies needs to be known
2* Researchers worldwide have tried to develop a soil
nitrogen test
3* Some researchers have successfully developed usable soil N
tests but soil N tests can have variable success across
regions and soil types
4* Some are also time consuming and expensive
