Crops

Question 1

3 production ecological principles

Answer 1

1. Potential Production (farmer cannot influence: temp, genetics, c02)
2. Attainable Production (farmer can take yield increasing measures: Water & nutrients)
3. Actual Production (farmer can take yield protecting measures: weeds, pests, diseases)

Question 2

3 Yield Gaps (Silva)

Answer 2

1. Efficiency Yield Gap
2. Resource Yield Gap
3. Technology Yield Gap

Question 3

Efficiency Yield Gap (Silva)

Answer 3

• difference between technical efficient yield &actual yield
• how much additional output can be produced given observed levels of inputs?

Question 4

Resource Yield Gap (Silva)

Answer 4

• difference between highest farmer yield & technical efficient yield
• Captures the trade-off between maximum yield and different resource allocation strategies

Question 5

Technology Yield Gap (Silva)

Answer 5

• difference between highest farmer yield & potential yield
• 2 types: 1) partial (requires the closure of the resource yield gap of another input) 2) complete (adoption of precision agriculture practices)

Question 6

Harvest Index (ratio)

Answer 6

HI = (DM economic product)/(Total DM)

Question 7

Fresh Yield (ratio)

Answer 7

FY = (Total DM x HI)/(1-moisture content at harvest)

Question 8

Nutrient Use Efficiency Limitation

Answer 8

Nutrient-use efficiency declines with increasing application

Question 9

Integrated Resource Management

Answer 9

• balance between crop production (short-term) and environment (long-term)
• resource use efficiency (RUE) and targeting organic and mineral sources of nutrients in order to reduce the residence time in the soil

Question 10

Synlocalisation

Answer 10

Nutrient application in space: applying in young fields where roots are active, trying to match demand and supply

Question 11

Synchronisation

Answer 11

Nutrient application in time: applying when the crops need it

Question 12

Resource Use Efficiency (RUE) ratio

Answer 12

Resource Use Efficiency (RUE) = (All useful outputs)/(All inputs)

Question 13

Resource Productivity (Ratio)

Answer 13

Resource productivity = (DM yield)/(Input (kg))
OR simply (Yield/input)

Question 14

Resource Use Efficiency (RUE)

Answer 14

RUE efficiencies differ at different application levels. RUE and productivity decline when application and inputs increase.

Question 15

NUE (Soil-Crop)

Answer 15

NUE=(N Uptake)/(N application+N deposition)

Question 16

2 types of fertilizer

Answer 16

1. Mineral: immediately available

2. Organic: slow decomposition and nutrients become available with time

Question 17

Legume Role in Ecological Intensification (+ limitation)

Answer 17

Legumes fix Nitrogen, but they need P, K and rhizobia

Question 18

Legume Functions

Answer 18

GAINS-C
• N fixation, reduced soil erosion, weed, pest, and disease suppression
• Cover soil surface , provide OM inputs , increase productivity
• Spread labour needs
• Improve efficiency of land use
• Animal food
• Grain legumes: ensure food security through improved diet and income

Question 19

SOM Functions

Answer 19

• Nutrient Supply
• Nutrient Buffer
• Water Buffer
• Soil Structure

Question 20

NUE EU Targets

Answer 20

min = 50% (below = inefficiencies)
max= 90% (above=soil mining)

Question 21

NUE Target Limitations

Answer 21

Boundaries, inputs and outputs, target values change with each system.
Also needs to include production and surplus as indicators for sustainability.

Question 22

NUE Limitations (as a measurement)

Answer 22

Use of nutrient resources constrained not only by their availability, but also by interrelated resources of land, labour, and capital

Question 23

N Inputs

Answer 23

MAD-F:

application, mineralization, deposition, and fixation

Question 24

N Outputs

Answer 24

HIV-DL:

harvest, immobilization, denitrification, leaching, and volitalization

Question 25

NUE (applic.)

Answer 25

(uptake (application)− uptake (no appl)) / (inputs (N appl + N dep))

Question 26

NUE (crop)

Answer 26

(N Uptake) / (N application+uptake (no appl) + N deposition)

Question 27

Stover

Answer 27

leaves and stalks of field crops that are left in a field after harvesting the grain

Question 28

C:N Ratio

Answer 28

Higher C = harder for soil organisms to decompose plant residues –> mulch

High N = high decomposition rate