Managing crops

Growing crops is probably the most common activity on any farm whether as the dominant activity of the farming system, as an additional income stream, or to produce food for the family. The main crops commonly included in CLEM are grain crops (e.g. maize and rice) and forage crops (e.g. Panicum, Lucerne, Lablab and Elephant grass), while vegetable crops (e.g. tomato, cucumber, chilli and tobacco) and tree crops (e.g. bananas, cashews and coconuts) can also be included. The model does not have specific parameterised crops and so allows any crop for which you have production data.

Crop and forage data

CLEM does not include any specific crop growth models, but relies on field data or other well established models of plant growth to provide data on crop production (e.g. APSIM crop models) and pasture growth (e.g. the GRASP model of Australian native pasture). This approach allows a wide range of other detailed models to be used to simulate crop and forage inputs for CLEM, but also means there is a disconnect between the farm simulation and the plant production, such that on-farm activities generally don't impact the plant production. For example, if there was insufficient labour available to perform fertilisation on the farm and this activity was skipped, the lack of fertiliser applied would not be apparent in the crop data from the external model. This shortcoming can be remedied in future by having direct links to APSIM Next Generation models running in the same simulation with additional means to reduce crop products below potential based on resource shortfalls being implemented. In other circumstances such as when labour and finance constraints planting and harvesting, the model can limit the harvested amounts accordingly.

The CLEM model uses a database of crop production to provide harvest dates and the biomass of products harvested (e.g. grain, fruit, pasture). While these will likely come from other models, as long as the data provided is in the correct format, it can come from any source including experiments, local knowledge or expert opinion. This Information is provided to the simulation by Crop data reader component. For example, to include a tomato crop, there will need to be a tomato entry in the database with harvest dates and the amount harvested (per hectare) provided for each date. In its simplest form this might be the same estimated value harvested every month of the year for continuous production, or the data may come from a detailed simulation model taking into account soil type and rainfall throughout the simulation.

Resources required

The resources involved can include land on which to grow the crop, labour needed to perform activities, finances required and a range of animal, human and graze food stores as well as product stores to store the crop products. Just about any resource could be required for growing crops as the task may also require water, draught ruminants, machinery and produce greenhouse gases.

Activities required

The Manage crop activity is responsible for requesting the land on which to grow a crop and managing all the cropping activities. This can probably be better thought of as "manage a field and associated tasks" as we'll see soon that a field can have multiple crops growing together or in a rotation (see Manage crop for full details).

Below the Manage crop activity are any number of Manage crop product activities that are responsible for managing harvest dates, retrieving the harvested amount from the crop files and placing it in the store specified. The variety of possible crops means that they can be placed in a range of resource stores including Animal food stores, Graze food stores,Human food stores and Product stores.

Each Manage crop product activity can contain any number of crop tasks with an associated Labour requirement and Crop fee. Crop tasks include activities such as preparing the field, planting, weeding, irrigating and harvesting each with a number of costs (e.g. seed purchase with planting task).

 

 

Unlike the precursor model (IAT) where a list of available cropping tasks were built into the model, CLEM provides the flexibility to add as many or as few cropping tasks as you like. Common tasks associated with growing a crop that are not already included in other activities include:

• Land preparation
• Ploughing
• Planting
• Fertilising
• Manuring
• Weeding
• Spraying
• Watering/irrigation
• Tree management
• Harvesting
• Post harvest
• Transporting
• Forage storage

Costs associated with these activities can include:

• Seeds/plants
• Bags and labels
• Storage costs

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