1. Relay cropping: Breakthrough to improve soil,
air and water quality
Mohsin Tanveer, Dr. Ehsan Ullah, Dr. Shakil Ahmad Anjum
Under the circumference of global warming and climate change, emanations of various
gases seem to be played most destructive role in changing climate. In agriculture, so
called chemical fertilizers or synthetic harmones are considered most effective
candidates for instant availability of nutrients. However, complete utilization or uptake
by plants is still a question. Not all amounts of available nutrients are used by the plant
then where they go. Excess nutrients either deteriorate water quality via eutrophication,
leaching or release into environment thus increasing temperature so nutrient
management is raised as new issue in global warming scenario. CO2 emissions are
considered the primary cause of global warming but under anaerobic conditions CO2 is
converted in methane gas which is 25 times more dangerous than CO2. Furthermore,
release of nitrous oxide from soil is 300 times more vicious than CO2. Nitrogen and
phosphorous are considered two most important nutrient and they are applied in very
high amount in crop production. Small amount of them are used while great amount of
these nutrients loss through eutrophication, soil erosion, leaching, volatilization or
immobilization. All these processes disturb sustainability of an ecosystem and
deteriorating soil, air and water quality. The challenges when dealing with
environmental issues that are perplexed by crop production and profitability of a farm.
Identification of any environmental problem takes time before it may become a possible
concern.
To combat these herculean problems and ensuring sustainability of an environment,
integrated approach should be used. Possible solution may be reduced utilization of
synthetic fertilizers which is not possible for small land holding farmers or may be use
of additional crop in main crop just to use excess available resources which has
potential to be accepted. Different case studies revealed that relay cropping has
potential to reduce the effectiveness of these problems. The inclusion of any scavenger
crop in main crop at a stage when main crop is at its maturity looks like to be a reliable
and approachable technique. That scavenger crop not only uses excess nutrients from
soil that might be lost latter but also produce biomass which is a source of additional

2. income for the farmer. Relay cropping is actually a synonym of crop diversification with
aims to increase planting intensity per unit area and net profit. Use of grain legumes in
standing main crop is an old approach but has little attention due to less productivity of
main crop. Farmer’s intention is to produce more from cash crop and for that he
applies extra nutrients and takes extra care of that crop but does not take care of his
soil. A famous line is used by many Agronomists that use the land according to its
capability. This means that apply nutrient to soil according to nutrient retention
capacity of soil. Excess nutrient may disturb chemical and physical properties of soil
and in future might be unable to cultivate any crop. Under all such situations, relay
cropping system is more productive one.
For instance, Corn production is the most favourable business in world due to high
price of corn. To get high yield farmers are using hybrid which are more fertilizer
responsive. Several studies in different countries demonstrated that soils on which corn
is produced have lost their retention capacities and underground water has more EC
and pH due to high concentration of salts in it. Later on, few scientist experimented
wheat and soybean relay intercropped in maize in different regions of world on
different soil series at farmers field level and they found that excess amount of nutrient
unused by maize was used by wheat and soybean. Thus that nutrient reduced the cost of
production and increased profitability of farm. They showed that wheat removed 146
Kg N/hac that could be lost via leaching. Wheat saved that amount of nitrogen by two
reasons: (1) it absorbed fall and spring precipitation, reduced available water for
nitrate in soil (2) By driving force of wheat roots, nitrates retained in rhizosphere thus
made it available for itself. However, the contribution of wheat towards overall
profitability of farm depends on amount of nitrogen availability and which depends on
management practices, taken previously. In this way relay cropping works and optimize
net profit, sustain the environment, conserve the resources. A lot of research in needed
to examine the effectiveness of relay cropping system in spatial variation of nutrients, in
various agro ecological zones.
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