– Grain can even at low potassium number grown without yield loss, while legumes, peas and faba bean, are more sensitive to potassium deficiency. On coarse sandy soil, there is no reason to maintain a high kaliumtal as it provides greater losses by leaching. But certain crops such as pea, broad bean and potatoes require injection of potassium in the spring (Early season), if potassium rates are low.
– Potassium is an essential nutrient for plants, but in organic crop rotations, it’s a must priority to the most potassium demanding crops. At the same time, do not try to keep a higher potassium number on sandy soil than necessary as it only increases the loss by leaching.
– If the field has a low potassium number, it is especially on coarse, sandy soil necessary to add potassium, if you want to grow potassium demanding crops such as field peas, faba bean, clover and potatoes.
– The plants can get potassium from the soil under the plowing layer or from the more inaccessible potassium pools in the ground. In other words, the potassium number does not show the total pool of potassium that plants can use. The larger the clay content in the soil, the greater the buffer of potassium there are in the soil.
Scientists have sternly warned that soil fertility in the country is under serious threat as a result of overuse potassium and this might highly undermine efforts to improve food security and sustainable agricultural productivity.
The observation was said yesterday in a two-day first national potash symposium in Dar es Salaam.
In simple terms, nitrogen promotes plant growth. It is associated with leafy, vegetative growth. It’s part of every protein in the plant, so it’s required for virtually every process, from growing new leaves to defending against pests.
Nitrogen is part of the chlorophyll molecule, which gives plants their green colour and is involved in creating food for the plant through photosynthesis.
Lack of nitrogen shows up as general yellowing (chlorosis) of the plant. Because nitrogen can move around in the plant, older growth often yellows more than the new growth.
Phosphorus is involved in metabolic processes responsible for transferring energy from one point to another in the plant. It’s also critical in root development and flowering. Because phosphorus moves slowly through the soil, it’s important to work it into the soil, where it’s needed by the roots.
Potassium helps regulate plant metabolism and affects water pressure regulation inside and outside of plant cells. It is important for good rood development. For these reasons, potassium is critical to plant stress tolerance.
The scientists acknowledged that the country’s soil fertility has reached a crisis level as a result of mining, agriculture and other uses and thus runs short of vital mineral nutrients, particularly potassium.
“For decades Tanzania and other East African Community member states have been using industrial nitrogen and phosphorous in the soil, leaving aside potassium on grounds that the soil was rich in the mineral,” African fertiliser agribusiness partnership (AFA) country director Dr Mbette Mshindo Msolla said.
Dr Msolla, who is also a scientist, said there was a burgeoning crisis in the country’s soil that requires bold actions to do away with it.
He said at the conference, jointly organised by the agriculture, food security and cooperatives ministry with support from the international potash institute (IPI), that already the side effects of potassium deficiency are evident on plants and human beings.
“Farmers are heavily complaining on poor yields. The deficiency has not been well documented by professionals,” he said explaining: “Shortage of potassium on horticultural produce, for instance, diminishes the quality, size and taste of fruits. On coffee for example, it also reduces the quality of leaves and affects productivity and market competence.”
Prof John Msaky, who is a soil scientist at the Sokoine University of Agriculture (SUA) made it clear that the problem was a serious one in the country.
Access to potassium fertilizers, he said, is another challenge especially for local markets.
“This is because people were told potassium is available and does not need replacement,” he said.
“Potassium is becoming more and more a serious problem,” he added. He went on to highlight that most of fertilisers recommended to farmers are outdated and that shortage of macro nutrients in the soil have serious consequences on the government attempt to transform the agricultural sector.
“The government has done its part, it’s our responsibility as multi stakeholders to make this transformation a reality,” he said.
The conference drew 50 delegates – agricultural experts, private sector stakeholders, agro-input agents, farmers’ association, fertilisers marketing companies and government officials.
Peniel Lyimo, who is deputy chief executive officer, president’s delivery bureau (PDB) emphasising the importance of potassium to plants and human beings said: “Potassium as a nutrient element is essential for vigorous growth, disease resistance, fruit and vegetable flavouring and development, and for general plant function.”
“Deficiency symptoms in maize, for instance, is yellowing areas along the leaf veins and leaf margins, and in other plants the leaves crinkles and rolls-up, and grows dead twigs. Fruit trees may develop fruit with poor flavour or less developed fruits. Potassium is also a very important mineral for the human body, as it involves various biochemical reactions.”
He said some of the notable potassium deficiency symptoms in human being include increased blood pressure, excessive sweating, fatigue, muscle weaknesses, etc.
“Foods containing potassium include meat, most vegetables and fruits,” he said.
He said it is, therefore, evident that our soils should contain adequate amounts of potassium that can be available for plant uptake and enter the food web.
Developed countries have recommended dietary daily intake of potassium based on age (infants, children/ adolescents and adults).
“As a nation, we should strategise to reach the level of obtaining recommended dietary daily intake of potassium for at least infants and children,” he added.
He said the country is struggling to increase agricultural productivity to feed the population of about 50 million, by intensifying productivity on a small piece of land, using improved agronomic practices.
“Agricultural intensification is therefore inevitable now than ever before, because of the challenges of population growth and climate change,” he said.