Multiple Cropping and Soil Productivity
Muhammad Waseem Abbas, Shakeel Ahmad Anjum, Nadeem Akbar, Iftikhr Ali, Nazer Manzoor, Abdul Shakoor, Muhammad Mahmood Iqbal, Ali Usman, Muhammad Bilal
Agro-Biology Laboratory, Department of Agronomy,
University of Agriculture, Faisalabad, Pakistan, 38040.
Multiple cropping and soil productivity are closely related to each other. In many areas still today, and some years ago mono cropping was done. Mono-cropping is the Agricultural practice of growing a single crop year after year on the same land, in the absence of rotation through other crops or growing multiple crops on the same land. Corn, Soybean and wheat are three common crops often grown using mono-cropping techniques. However, to feed the projected population of the mid-21st century even at present levels, not to mention a level approaching that of developed countries, agricultural efficiencies would have to be far greater than is currently the case in most countries. We need increases in agricultural productivity of between 1.8% and 3% per year for many years. This can occur only if crop intensity is increased leading towards Multiple Cropping. In Agriculture, Multiple Cropping is the practice of growing two or more crops in the same piece of land during a single growing season. It is a form of polyculture. It can take the form of double-cropping, in which a second crop is planted after the first has been harvested, or relay cropping, in which the second crop is started amidst the first crop before it has been harvested. Soil productivity is defined as the capacity of soil, in its normal environment, to support plant growth. Soil productivity is reflected in the growth of forest vegetation or the volume of organic matter produced on a site. Multiple cropping is highly sustainable as it relies on reducing competition and increasing mutual benefits between crops. It can provide a more efficient use of resources, such as soil nutrients, that would not otherwise be available to a single crop; support or shade a companion crop; or host a great diversity of insects, bacteria and other organisms that contribute to pest and disease control. Nitrogen is essential for plant growth but it is often lost from the soil through unsustainable agricultural and soil management practices. Multiple cropping with nitrogen-fixing legumes can improve soil quality by replenishing the soil with N. Increased N in the soil decreases the reliance on both organic and inorganic fertilizers, reducing the amount of money and labor farmers need to spend on inputs. At the same time, the natural capital of the soil is conserved. Increasing the availability of N in the soil is associated with improved crop growth, which can in turn improve the livelihood of the farmer. Further, incorporating nutrient dense crops such as legumes into the rotation can increase farming house-holds access to nutritious foods, improving their nutrition security.
Benefits of multiple cropping systems in soil productivity:
Multiple cropping of compatible crops can encourage biodiversity, by providing a habitat for a variety of insects and soil organisms that would not be thrive in a mono-crop environment. In turn, this may limit the number of outbreaks of pests by increasing the number and diversity of natural predator biodiversity. Micronutrient deficiencies, a sub-set of under nutrition, occur when the body lacks one or more micronutrients (such as iron, iodine, zinc, vitamin A). Multiple cropping with crops that are bio fortified with micronutrients such as Vitamin A orange fleshed sweet potato can add further nutritive value per hectare. Multiple cropping acts as an insurance against failure of crops in abnormal weather conditions. The risk of total crop failure due to uncertain monsoon is reduced if two crops of a different nature are grown simultaneously as a mixed crop. Multiple cropping reduces the risks of erosion by limiting the time period for fallow land. From multiple cropping systems, regular additions of organic matter improve soil structure, enhance water and nutrient holding capacity, protect soil from erosion and compaction, and support a healthy community of soil organisms.
Limitations in multiple cropping systems:
Multiple cropping systems severely damage the organic matter of the soil and decrease the soil productivity. Addition of continuous inorganic nutrients cause binding as well as fixation. Wheat, Rice, Cotton and Sugarcane are mostly sown, exhaustive crops, reducing the organic matter of the soil. It may also lead to erosion of the soil. Soil erosion causes degradation of soil. It also causes the loss of productive profile of soil. Certain insects, pests and diseases may spread easily from one crop to the next through crop residues. An important function of soil is to buffer and detoxify chemicals, but soil’s capacity for detoxification is limited. Pesticides and chemical fertilizers have valuable benefits, but they also can harm non-target organisms and pollute water and air if they are mismanaged. Compaction reduces the amount of air, water, and space available to roots and soil organisms. Compaction is caused by repeated traffic, heavy traffic, or traveling on wet soil during multiple cropping system.
To improve agricultural productivity, a number of things must be accomplished:
We have to reduce the present rate of degradation and loss of productive farmland due to erosion, salinization, waterlogging, and nutrient depletion. Crop yield can be improved on current agricultural land by improving tillage methods to preserve soils and nutrients. Agricultural practices should be reformed to be less harmful to forests and forest regeneration. Among these reforms could be reductions in the use of burning, minimizing the use of toxic chemicals, and land less intensively by increasing fallow times. Zero tillage agriculture should also be utilized. Environmental impacts of new technologies should be reduced by reducing artificial inputs. Policies should be reformed relating to water management, allocation, and distribution. Local people may be identified and trained and Extension workers to change the attitudes of farmers