Cereals 2024 Week 8 Crop Nutrition Nitrogen Part 1 Handout
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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