While rotating crops or leaving fields fallow for several growing seasons is good practice, some farmers do not have this luxury, needing to continue planting season upon season. However, this practice will soon see soils depleted of nutrients. In these cases, use of green manure, and organic fertilisers is recommended. In. the last-resort cases where chemical fertilisers must be used, banding and micro-dosing are approaches that rationalise or minimise application. Banding is the agricultural practice of placing fertiliser in a row below soil surface, covering with soil and planting seeds above the fertiliser, whereas Micro-dosing – sometimes referred to as ring-placement - is the practice of placing small, more affordable amounts of fertiliser around each crop plant. Banding is a common method used for basal fertiliser applications and uses less fertiliser than broadcasting as it is applied in rows rather than throughout the whole field. Micro-dosing is applicable where plants are widely spaced and where soil increases the chances of nutrient loss due to leaching. While the use of chemical fertilisers is not strictly considered climate smart, these practices promote economic and rationalised application of fertilisers, reducing greenhouse gas emissions, whilst improving resilience in the face of climate change, and providing options for maintain agricultural productivity.
To effectively leverage banding and micro-dosing for maize and sorghum, the following should be carried out. When handling fertilisers, always ensure that safety precautions provided on the packaging are followed.
Banding – suitable when wishing to save on fertiliser expenditure, but still need to improve production of primary and secondary crops.
- Step 1: Plough the field using a draught animal-drawn or mechanised plough to carefully open furrows. Depending on availability of mechanised equipment, a narrow hoe can also be used if manual labour is favoured. This can reduce workload and minimise soil disturbance but may require more effort.
- Step 2: Count furrows and measure length to ensure that you have sufficient fertiliser for area, based on recommended application amounts (see packaging or see advice from supplier).
- Step 3: Apply fertilisers as a strip or line (band) along the furrow.
- Step 4: Turn furrow back over ensuring that the fertiliser is present at a depth of 5-8cm below the soil surface and covered by the soil. The basal fertiliser should not touch the seed as it may burn it and disturb its germination.
Micro-dosing: suitable when fertiliser is in short supply.
- Step 1: in the field, at the time of planting, prepare small pits 5 to 8 cm deep where each seed is to be placed.
- Step 2: measure approximately 6 grams of fertiliser using a bottle cap or a three-finger pinch.
- Step 3: place the micro-dose in the small pits.
- Step 4: cover fertiliser with a small amount of soil, then place the seed. Cover fully with soil and water, or allow rain to wet the ground.
- Where manure is available, Zai pits can be used to improve organic matter at the same time. Prior to planting, dig the small pit and fill with manure. When rains begin, fertiliser and seed are placed in the hole and covered.
- The practice includes the advantage of banding by placing the fertiliser below the seed but at a single point instead of a row.
- Agriculture for Impact 2019. Microdosing. Agriculture for Impact website.
- The Food and Agriculture Organisation (FAO), 2003. On Farm Composting Methods; Land Water Discussion Paper 2. Rome, Italy.
- ICRISAT 2009. Fertiliser Microdosing: Boosting Production in Unproductive Lands. Andhra Pradesh, India.
- ICRISAT 2015. Brief 2: Fertiliser microdosing increases agriculture productivity. ICRISAT, Andhra Pradesh, India.
- International Fertiliser Development Centre (IFDC), 2018. Fertiliser Deep Placement. Alabama, USA.
- Soil Management India N.D. Application of Fertiliser to Soil: 6 Methods. Soil Management website.
Benefits
- Banding is the most commonly used method for basal fertiliser applications, and it uses much less fertiliser as it is applied in rows.
- Micro-Dosing maintains and increases crop production with less fertiliser, crops become less susceptible to diseases/pests and reduces GHG emissions per kg of crop produce.
- Micro-dosing has been known to double or even triple yields and plant biomass.
- If using fertiliser, these approaches can save significantly on the cost of fertilisers, as is
- Can be used to supplement organic fertilisers if in short supply.
- Both techniques are more economic for smallholders.
Drawbacks
- Use of chemical fertilisers has a cost attached.
- Chemical fertilisers are not strictly a CSA approach.
- Requires a sustainable supply of fertilisers.
- If small-holders are purchasing fertilisers, they are often only available in 50 kg bags, which often make them economically inaccessible. Agriculture for development projects have been lobbying manufacturers to also provider smaller bags.
- If 50 kg bags are purchased, fertiliser must be stored in cool dry place – following instructions on packaging.
- Micro-dosing can be very time and labour intensive.
