3 production ecological principles
- Potential Production (farmer cannot influence: temp, genetics, c02)
- Attainable Production (farmer can take yield increasing measures: Water & nutrients)
- Actual Production (farmer can take yield protecting measures: weeds, pests, diseases)
3 Yield Gaps (Silva)
- Efficiency Yield Gap
- Resource Yield Gap
- Technology Yield Gap
Efficiency Yield Gap (Silva)
- difference between technical efficient yield &actual yield
- how much additional output can be produced given observed levels of inputs?
Resource Yield Gap (Silva)
- difference between highest farmer yield & technical efficient yield
- Captures the trade-off between maximum yield and different resource allocation strategies
Technology Yield Gap (Silva)
- 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)
Harvest Index (ratio)
HI = (DM economic product)/(Total DM)
Fresh Yield (ratio)
FY = (Total DM x HI)/(1-moisture content at harvest)
Nutrient Use Efficiency Limitation
Nutrient-use efficiency declines with increasing application
Integrated Resource Management
- 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
Synlocalisation
Nutrient application in space: applying in young fields where roots are active, trying to match demand and supply
Synchronisation
Nutrient application in time: applying when the crops need it
Resource Use Efficiency (RUE) ratio
Resource Use Efficiency (RUE) = (All useful outputs)/(All inputs)
Resource Productivity (Ratio)
Resource productivity = (DM yield)/(Input (kg)) OR simply (Yield/input)
Resource Use Efficiency (RUE)
RUE efficiencies differ at different application levels. RUE and productivity decline when application and inputs increase.
NUE (Soil-Crop)
NUE=(N Uptake)/(N application+N deposition)
2 types of fertilizer
- Mineral: immediately available
2. Organic: slow decomposition and nutrients become available with time
Legume Role in Ecological Intensification (+ limitation)
Legumes fix Nitrogen, but they need P, K and rhizobia
Legume Functions
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
SOM Functions
- Nutrient Supply
- Nutrient Buffer
- Water Buffer
- Soil Structure
NUE EU Targets
min = 50% (below = inefficiencies) max= 90% (above=soil mining)
NUE Target Limitations
Boundaries, inputs and outputs, target values change with each system.
Also needs to include production and surplus as indicators for sustainability.
NUE Limitations (as a measurement)
Use of nutrient resources constrained not only by their availability, but also by interrelated resources of land, labour, and capital
N Inputs
MAD-F:
application, mineralization, deposition, and fixation
N Outputs
HIV-DL:
harvest, immobilization, denitrification, leaching, and volitalization
