In the present era, due to shrinking land resources and a rapidly growing population, intercropping is being considered a better alternative to traditional monocropping systems. Traditional agricultural practices like the monocropping system are no longer adequate to meet the rising demand for food. Using chemical fertilizers has significantly increased agricultural productivity and reduced the recent food crisis. In a monocropping system, increases in food production and crop output are mostly achieved through heavy fertilizer use and irrigation, which ultimately have increased environmental problems such as severe water and air pollution, acidification of the soil, and erosion, posing unprecedented challenges to food security and sustainability.
Intercropping refers to the cultivation of two or more crops simultaneously on the same piece of land in a specific row arrangement or proportion. This system not only increases yield per unit area but also plays a key role in maintaining environmental diversity and soil health. Inclusion of legume crops like soybeans is advantageous for the sustainability of a cropping system. Soybean crop plays a significant role in supplying human and animal feed with protein and vegetable oil, accounting for 3.3% of global caloric consumption. Soybean production was estimated at 362.1 million tons in 2020-2021, making it one of the most significant global commodities.
Efficient Utilization of Resources
The fundamental concept of intercropping is based on the principle of complementarity. When crops with different heights and root systems are grown together, they utilize available resources more efficiently.
Water use efficiency
Water availability in the cropping system affects plant development. Intercropping can boost the efficacy of resource utilization, as light, water, and fertilizer, to greatly increase the production of land per unit area. Additionally, this can boost water production efficiency and yield financial gains for farmers. Intercropping is beneficial because it enhances the amount of photosynthetic sources (leaf area index and leaf area duration), accelerated the movement of photosynthates from vegetative organs to grain, and promotes water use efficiency, which in turn raises production.
Grain yield increased in intercropping systems as compared to sole cropping, owing primarily to improved leaf area index and photosynthesis, along with increased leaf chlorophyll content. Intercropping increased soil water conservation and reduced soil runoff, while it improved water use and system productivity.
Nutrient use efficiency
Intercropping has a potential advantage over monocropping as higher grain yield, greater resource use efficiency for nutrients, water and sunlight and reduced insect pests and diseases. The crop yield advantage in an intercropping system is mainly due to the increase in nutrient use efficiency, nutrient uptake and its utilization efficiency. Higher nutrient uptake in intercropping results in more dry matter accumulation and productivity. In this system, plants compete for soil and fertilizer which improves the ability of nitrogen fixation by leguminous plants. To improve the yield benefit from nutrient uptake in intercropping, the nutrient utilization efficiency must be increased when compared to sole cropping.
Radiation use efficiency
Intercropping offers the advantage of capturing and utilizing more solar radiation compared to monocropping. In an intercropping system, row spacing between two crop species decreases, which covers the soybean crop. This increase in canopy cover reduces the solar radiation and temperature to reach the soil surface and reduces the loss of mineral nutrients (N and P) from the soil, thereby enhancing nutrient uptake, crop yield and system productivity.
When other factors of growth are not limiting, crop productivity is derived from the extent to which radiation is used by the plants. Some other researchers also concluded that the shade effect on intercrop plants increases, the radiation use efficiency as compared to the main crop in the cropping system. Some other studies reported that intercropped legumes use solar radiation more efficiently than sole cropping, as in the maize-soybean intercropping system.
Soil Resources
Roots of different depths extract water and nutrients from various soil layers, thereby minimizing competition between crops. Intercropping protects soil from desiccation and erosion by providing year-round or, at the very least, long-term ground cover than monocropping. Surface pores can be clogged by rain, preventing water from reaching the soil and causing surface erosion. Protecting the soil from compaction is a primary goal of intercropping with legumes. Under intercropping system soil organic matter accumulates over time which improves soil aggregation and helps reduce soil erosion, and combined together, these lead to improved soil structure, water infiltration rate and water productivity. Soil depletion was better protected when cowpea was intercropped with maize because of its ability to disguise the soil surface and lower soil erosion.
Biological Nitrogen Supply
The cultivation of legumes along with cereal crops naturally enhances soil fertility. Bacteria present in the roots of leguminous plants fix nitrogen from the atmosphere and transfer it into the soil. This partially fulfils the nitrogen requirement of the associated crop and reduces dependence on synthetic fertilizers.
Nitrogen (N) is a crucial element for plant growth, playing a significant role in photosynthesis, particularly in leaves, where more than half of the nitrogen is allocated to the photosynthetic apparatus. Cereal-legume intercropping system performed well with soil N or the application of synthetic N is less, as legumes help in balancing the N deficiency. This is primarily because nitrogen limitation promotes atmospheric N2 fixation in legumes, thereby reducing interspecific nitrogen competition and enhancing complementary nitrogen use between cereals and legumes. Similarly, phosphorus (P) is one of the essential macronutrients playing a pivotal role in energy transfer, signal transduction, macromolecular biosynthesis and overall metabolic regulation. In sole maize, adequate phosphorus availability is crucial for achieving optimum yield and maintaining physiological functions. Whereas, intercropping boosted the maize yield (34%), phosphorus use efficiency, phosphorus partial factor productivity, and aboveground phosphorus uptake by 37-137%.
Biological Control of Pests and Diseases
Due to increased diversity, the risk of pest attacks is reduced in intercropping systems.
Barrier Effect
Plants of one crop act as a physical barrier against pests of another crop.
Weed Suppression
The presence of an additional crop on the soil surface suppresses weed growth. Intercropping ensures greater utilization of resources, a lower population of hazardous organisms, more resource conservation and soil health, and a higher level of production. Due to biochemical effects, intercropping of allelopathic crops with other crops may not only increase weed control in the main crop but also enhance the nutrient availability and microbial activity in the soil. Weed control was excellent when intercropping was combined with optimal row spacing and hand weeding. Intercropping pea in wheat crop at various ratios dramatically reduced weed density and fresh and dry biomass and also yielded higher economic returns. Intercropping is more effective in controlling weeds, improving nutrient use efficiency and increasing organic matter in soil than monocropping.
Intercropping effect on farm productivity and sustainability
Since monocropping systems use more inputs to enhance the system’s productivity, it often results in compromised soil health, water and atmosphere quality due to nitrate emission, pesticide leaching and runoff, and greenhouse gas emissions, to name a few. On a long-term basis, it leads to declined farming system’s sustainability. To enhance the system productivity and sustainability, intercropping remains the best option. A well-designed intercropping system uses all natural resources efficiently, increases biodiversity, reduces insect and pest attack, and increases crop productivity and soil fertility. It also produces more yield, reduces labour costs, and provides economic benefits.
Sustainable agriculture uses resources like soil and water more effectively and maintains ecological balance. Contemporary sustainability concerns in designing agricultural practices and technologies that
- Do not harm the environment as a valuable resource,
- They are practical and accessible to farmers, and
- Increase food productivity while making it environmentally friendly as well for goods and services.
Depletion of natural resources in conventional farming practices and monoculture systems results in environmental pollution. One strategy for boosting diversity in an agricultural ecosystem is intercropping.
Owing to better crop growth rates, decreased weeds, pests, and diseases, and more efficient use of resources, intercropping boosts crop output. Due to pest or pathogen attraction by the second crop species in an intercropping system, pest and disease damage is less pronounced than in sole cultures.
Importance in Pakistan’s Economy: The Maize–Soybean System
Under the current agricultural and economic conditions of Pakistan, intercropping—especially the maize–soybean system—holds great importance.
Reduction in Import Bill
Pakistan spends billions of dollars annually on the import of soybeans and edible oils. Intercropping soybeans with maize can increase local production and save valuable foreign exchange.
Stability in Poultry Feed
Maize and soybeans are two essential components of poultry feed. Their simultaneous cultivation can reduce feed costs, directly benefiting the poultry industry and consumers.
Economic Stability and Risk Management
For farmers, this system acts as an economic safeguard. If one crop is affected due to climate change or disease, the income from the other crop helps reduce financial risk.
Support for Small Farmers
This system provides food security and a stable income source for small-scale farmers.
Intercropping is not only a scientific method to increase per-acre yield but also essential for improving soil health and farmers’ economic conditions. Promoting this technology in Pakistan can significantly support the national economy and contribute to sustainable agriculture.
Rukhsar Saleem1, Muhammad Zia ul Haq2, M. Abdullah Saleem3, Wajeeh Ur Rehman4
1,2 University of Agriculture Faisalabad,
3 Green Gold Company,
4 Ayub Agriculture Research Institute
