pH is a scale that chemists use to measure acidity. Values below 7 are considered acidic, values above 7 are alkaline (the opposite of acidic) and 7 is neutral. Most plants can tolerate a wide pH range in solution culture, but they cannot tolerate a wide range of acidity in the soil
Under acidic conditions, many soil minerals dissolve and increase the concentration of metal ions to toxic levels. The primary toxic metal is aluminum, but high levels of manganese and iron can also inhibit plant growth under these conditions. The nutrients phosphorus and molybdenum are less available in acidic soils and calcium and/or magnesium may also be deficient.
Under alkaline the solubility of minerals decrease to the point that nutrient deficiencies occur. Plant growth is therefore limited by deficiencies in iron, manganese, zinc, copper and boron. Phosphorus is also less available in alkaline soils and high levels of calcium may inhibit the uptake of potassium and magnesium.
The aim in managing soil pH is not to achieve a particular pH value, but to adjust the acidity to the point where there are no toxic metals in solution and the availability of nutrients is at its maximum. This condition is usually achieved when the soil pH is between 5.8 and 6.5; however some plants have special acidity requirements.
Agronomic soil tests use a chemical extraction solution to measure extractable macronutrients such as phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg), and micronutrients generally including iron (Fe), manganese (Mn) and zinc (Zn). Most soil tests also measure soil organic matter and soil pH. When paired with data from crop research trials, the agronomic soil test results can be used to determine crop specific nutrient needs for profitable and environmentally sound applications of fertilizer, manure and lime. Soil test results and management guidelines are only as accurate as the sample itself, so taking a representative sample of the field is essential.
Temperature - Maize requires 21- 30°C daily temperature for adequate growth and development and at least 8 hours of direct sunlight daily in order to grow its best.
Rainfall- A rainfall of 600-900 mm of rain is the average water requirement for the entire growing season. Best yield is usually 1,200-1,500 mm average especially under irrigation. It is fairly drought tolerant up to five weeks, but thereafter is very susceptible and therefore adequate rainfall after five weeks. Dry weather at flowering time seriously affects pollination and hence yields. Maize is very susceptible to frosts
Soil pH of 5.5 - 7.0 is the average soil pH requirement for maize but 5.8 is ideal
Soil type: Maize can be grown on many soil types, but performs best on well-drained, fertile medium textured well-aerated, deep soils containing adequate organic matter and well supplied with available nutrients. Alluvial loams, deep latosols and clay loams are preferred.
Hybrid selection is a critical component of any profitable maize production system. Many farmers are so focused on price but money spent on good quality certified hybrid seed is another ideal option of being successful. Great top quality hybrid maize varieties are the best investment. Be careful when you are choosing your maize varieties. The cheapest varieties could cost you the most money. Skillful hybrid selection requires that growers to Understand the field environment Know how a maize plant grows and develops and collect and properly evaluate information describing the characteristics of hybrids available in their area.
Ensure you timely prepares your land by ploughing early during the sunny season, give two or three ploughing if necessary to get good clean seedbed. Early planting at the onset of the rains ensures the plant benefits from nitrogen flush. The plant can also best out-compete weeds and escape disease incidences contributing to better yields. Yields are greatly reduced by late planting
The maize growing zones in Kenya are categorized according to the elevations above sea level and expected moisture requirements of the hybrids. The zones are classified as: Highland Maize Varieties, Medium Altitude agro eco-zone, Transitional zone, Dry land Hybrids, lowland and Coastal Varieties
Highland Maize Varieties: - These varieties are bred and recommended for high altitudes (1500-2400 m). Rainfall requirement ranges from 800-1500 mm. Examples of the varieties are: - H614, H625, H626, H628, H629, H9401, H6210, H613 and H6218
Medium Altitude Agro-Eco-zone- The altitude range for these varieties are Altitude range is between 1000 and 1800 m. These varieties are commonly grown in coffee growing belts maturing in 4-5 months. The ideal rainfall amount is between 750-1000 mm. Some of the varieties in this category include H513, H515, H 516 and H522
Transitional Zone=The altitude in this zone falls between 1000 and 1500 m where the temperature ranges from 12 to 30°C and has rainfall range of 800-1200mm. Typical examples are Hybrid 624 and H520.
Dry land Varieties
The variety performs well within altitudinal range of 500 m -1000m above sea level and is a variety for marginal rainfall areas. Rainfall required is 250-500 mm of rain and these are the arid marginal areas in many parts of Kenya. Examples in this category include Hybrids DH02,DH02, DH04, and SDTV01 (open pollinated variety).
Lowland/Coastal Agro-Ecozone - Lowland Low land varieties produced by the company for this ecozone grow in an altitude range of 0-1250m a.s.l., Higher altitudes being the lake regions. The Minimum amount of rainfall is 400mm per annum. Examples are Pwani Hybrids PH1 and PH4
What’s the difference between Conventional land preparation and Minimum Tillage (Conservations Tillage?)
Conventional land preparation
Conventional tillage is the cultivation of the soil using plough, harrow and other farm tools or mechanical implements to prepare the field. Plough at a depth of 15-20 cm when soil moisture is right. This allows the soil particles to separate and only thin portions sticks to the finger but no ball is formed. Harrowing is done twice with 2-3 passings to break the clods. If a disc plough is used, plough under maize stovers at a depth of 18-20 cm. For a disc plough the maize stovers are cut into small pieces and incorporated into the soil to act as compost when decomposed. Clay and weedy fields require two or more ploughing and several harrowing intervals.
Minimum tillage (conservation tillage)
Minimum tillage can be defined as the least amount possible of cultivation or soil disturbance done to prepare a suitable seedbed. Conservation tillage is the planting or sowing in the previous crop's residues that are purposely left on the soil surface. This means that the soil is not physically inverted and the process of ploughing the land is not used at any stage during seedbed preparation Instead, herbicides (Glyphosates) are used to clear the weeds before furrowing. Minimum tillage reduces energy consumption, labor costs, conserve moisture and retain plant cover to minimize erosion
This approach is important to the farmer who wants to make the best profit margins in terms of; Field efficiency, Fuel economy, Work rate and Land care. This approach however requires specialized implements to be used after some time e.g. strip ripping technology and no till planters. minimum tillage is used when weather conditions are excellent.
What amount of fertilizer do i use in my maize Crop:-
The amount of fertilizer to be used is determined by the fertility level of the soil. Maize is a heavy feeder of Nitrogen. Carry out soil analysis in specific farm to determine the nutrient status and needs. Nutrients are supplied as basal (Planting) and top dressing. For basal fertilizers apply about 20 Kg (Nitrogen) N /ac (100kg of planting Fertilizer) and 50 Kg of Phosphorous (P205) per acre. For the top dressing fertilizers apply 50kg of Nitrogen (75-100kg of top dressing fertilizer) per acre. Other essential nutrients that may be limiting should be applied based on the soil analysis and using Nutrient sources from various NPK fertilizers available. Farmers are encouraged to avoid acidifying fertilizers
What are the Characteristics of certified seed?
When farmers purchase certified seed they are assured or proper variety as per the recommended agro ecological zone and cropping seeds. Certified seeds also are viable, true to type and free from borne disease and pests with high yield potential. Good quality seed has various advantages among them uniform germination avoiding replanting or gap filing, vigorous seedling growth which reduces weed and disease damages. Uniform growth stages, maturity and products
When seed has good physical, physiological, health and genetic qualities, farmers have greater prospects of producing a good crop. High quality seed is a major factor in obtaining a good crop stand and rapid plant development even under adverse conditions.
What are the recommended plant spacing / Plant Population?
A grower should also select a plant population that complements his package of production practices Plant population is a critical factor in maize production. . Under spacing (sparse population) or over spacing (crowding) are both uneconomical. They negatively affect the yield of a crop. They lead to inefficient or wasteful use of resources such as fertilizer. Poor plant population might be caused by poor planter calibration. Thinning can be done in the case of crowding to ensure plant populations are within recommended practice. The recommended spacing is 75cm between rows and 25-30cm within row to give a plant population of between 22000 and 24000 plants per acre. . Approximate seed rate is 10 kg/ac.
Maize is affected by many pests and if not controlled adversely affect yield. Some early season pests and diseases are overcome by chemical seed treatment or breeding for tolerant varieties. Pests can either be insects, fungi, bacteria, virus, nematodes and predators. The damage of pests causes Necrosis (death of cells), wilting (blockage of water conducting tissues), soft rots breakdown of tissue structures) tumours (abnormal growth), yellowing, shortening of internodes, sterility proliferation of lateral shoots and root reduction, low plant vigour. Pest control ensures that pests are kept within the threshold levels that are not injurious to the plant. This can be done through preventive measures or when pest population reach economic injury levels mitigation measures need to be put in place by use of insecticides or fungicides and other pesticides. The use varies depending on target pests and mode of action.
The first fight against pest management is field scouting to inform control measure at a preventive or curative levels. Field scouting should be done as often as possible.
What are the common pests of Maize?