Appendix 5: Weed Management – Lesson from Brazil
In sugarcane, weeds have been estimated to cause 12 to 72 % reduction in cane yield depending upon the severity of infestation.
The nature of weed problem in sugarcane cultivation is quite different from other field crops because of the following reasons
• Sugarcane is planted with relatively wider row spacing
• The sugarcane growth is very slow in the initial stages. It takes about 30 - 45 days to complete germination and another 60-75 days for developing full canopy cover
• The crop is grown under abundant water and nutrient supply conditions
• In ratoon crop very little preparatory tillage is taken up hence weeds that have established in the plant crop tend to flourish well
Weeds flora in sugarcane field besides competing for moisture and light also remove about 4 times N and P and 2.5 times of K as compared to crop during the first 50-days period. Weeds also harbour certain diseases and pests that attack sugarcane and thus lead to indirect losses.
Weeds that are present in the furrows i.e., along the cane rows cause more harm than those present in the inter-row spaces during early crop growth sub-periods. Thus the initial 90-120 days period of crop growth is considered as most critical period of weed competition. Therefore the weed management practice adopted should ensure a weed-free field condition for the first 3-4 months period
Fertigation (Fertilizer + Irrigation)
Sugarcane being a giant crop producing huge quantity of biomass generally demands higher amounts of nutrient elements. A large number of research experiments have clearly demonstrated that for producing higher cane and sugar yields on a sustainable basis application of adequate amounts of fertilizer nutrients viz., N, P and K is essential.
At the same time the cost of chemical fertilizers has increased and there is a need to improve fertilizer use efficiency for more benefits. The best answer to this challenge is "Fertigation", where both water and fertilizers are delivered to crop simultaneously through a drip irrigation system. Fertigation ensures that essential nutrients are supplied precisely at the area of most intensive root activity according to the specific requirements of sugarcane crop and type of soil resulting in higher cane yields and sugar recovery.
Fertigation Offers Several Distinct Advantages in Comparison to Conventional Application Methods:
• Distribution of plant nutrients more evenly throughout the wetted root zone resulting in increased nutrient availability & uptake contributing to higher crop growth rates and cane yields
• Supply of nutrients incrementally according to the crop developmental phases throughout the season to meet the actual nutritional requirements of the crop
• Careful regulation and monitoring the supply of nutrients
• Application of nutrients to the soil when crop or soil conditions would otherwise prohibit entry into the field with conventional equipment