• May 24th, 2019
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Delayed planting decreases yield potential


The planting operation is one of the most crucial aspects in crop farming that affects potential yield. It is a time when seeds or seedlings are placed in the ground to establish the crop. If poor establishment occurs, yield potential is immediately limited. However, with recent changes in rainfall patterns most rain-fed grain farmers are uncertain as to whether to plant and when to do it, resulting in delayed planting. It is important to note that the later crops are planted, the lower the yield. Traditionally, dry planting commences in November and in some areas in October in anticipation of the first rains. However, due to the effects of climate change, the rainy season has become shorter, starting late (i.e. end of December) and ending earlier than normal. It is, however, of concern that many farmers still use outdated farming techniques and timing. It is imperative that farmers adapt new farming techniques to alleviate the effects of climate change. Factors to consider when planting include: 

Timing: 
Planting time has a major effect on crop yield. For most crops, there is an optimum planting time, which depends on climatic conditions and the time it takes for the crop to reach maturity. Conventionally, the highest yields are obtained with early planting. However, due to climate change, planting early may only be feasible when there are good early rains, as crops may not have sufficient time to reach their full physiological stage. Thus, in the context of delayed rainy seasons, farmers are advised to plant early maturing grain crop varieties (e.g. Kangara, Kashana, Nakare & Shidimba) that can survive drought conditions and mature within a short period (i.e. three months) to achieve better yield. 

Spacing: 
The spacing of plants in a row determines the ultimate plant population. The closer the spacing, the more plants there will be per unit area. A high plant population is only appropriate for early-planted crops under high rainfall or irrigated conditions with good management. However, given the current climatic variations, a lower plant population is recommended under dryland conditions. 
Spacing should depend on the crop type, cultivar and very importantly the climatic conditions (e.g. rainfall availability). In dry conditions, wider spacing is preferable in order to provide more soil water to the individual crop. Thus, farmers that plant too closely are advised to thin their crops at least two weeks after emergence to avoid competition. 

Depth: 
The sowing depth of a crop depends on the timing of planting, the size of the seed, the type of soil (e.g. clay or sand soil) and the weather conditions. Generally, smaller seeds are sown at a shallower depth than larger seeds (e.g. maize (5cm) may not be planted at the same depth as small seeded grain such as pearl millet (2.5-4cm)). It should be noted that the deeper the seed is planted, the longer the seedling will take to emerge and the weaker the plant will be at emergence. This may also reduce plant vigor and yield. Under rain fed conditions, when dry planting, deeper planting is recommended to ensure light showers do not reach the seed (e.g. pearl millet – 5cm). Farmers should also avoid covering the seed with clods or rocks to achieve good seed-soil contact. 
*This article is compiled by Emilie Abraham, Technical Officer within Agribank’s Agri Advisory Services Division
Varietal choice: 
The choice of seeds and cultivars should depend on their yield potential, amount and distribution of rainfall, growing season duration, planting date as well as soil fertility amongst other factors. Early maturing crops have short growing seasons (i.e. three months) compared to long and medium maturing crops that take longer to reach their full physiological stage. Thus, farmers are advised to start planting a portion of a field with later maturing crops and end with earlier maturing crops (i.e. Kashana and Kangara, which are bred to withstand drought conditions). 
Finally, farmers in the country are advised to work closely with their agricultural extension officials to receive guidance on selecting appropriate types of seeds and cultivars that are drought resistant. These seeds are subsidized by the Government of Namibia (GRN) and offered at an affordable rate. 


New Era Reporter
2019-02-12 12:22:00 3 months ago

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