In Bangladesh, in terms of food security for the increasing population and the transformation of agrifood systems, the dominant double-cropping based pattern of rice–rice is becoming less profitable and sustainable. Recent research found that a four crop-based cropping system, which includes aus (pre-monsoon rice), aman (monsoon rice), lentil (Lens culinaris), and mungbean (Vigna radiata), was more profitable than the double or triple crop cropping systems, and farmers can easily follow this new system. This newly adopted cropping system may increase farm income while creating job opportunities, alleviating poverty, and ultimately creating positive changes in the farmers’ livelihoods.
The increasing cropping intensification globally has led to soil nutrient depletion and a large increase in the requirement for nutrients coming from external sources for crop production. The application of fertilizers containing nutrient sources such as nitrogen (N), potassium (K), and phosphorus (P) replenishes some of the nutrients depleted by intensive cropping.
However, inadequate use of fertilizers will not replenish other depleted nutrients properly and will have a negative effect on soil health and crop nutritional security. The intensive cropping systems aim for yield maximization, involving the efficient use of all inputs (particularly fertilizers and plant protection chemicals, varieties of crops and livestock, and mechanization). Among the inputs, fertilizer has had a central role in increasing system productivity rapidly for more than four decades around the world.
In Bangladesh, in terms of food security for the increasing population and the transformation of agrifood systems, the dominant double-cropping based pattern of rice–rice is becoming less profitable and sustainable. To increase crop productivity in a system, increase land-use efficiency, and achieve a higher economic return and crop diversity, further intensification of cropping is required. Among developing countries, Bangladesh employs cropping intensification for increased crop production in an exemplary way with an average cropping intensity reaching 200%.
Recent research found that a four crop-based cropping system, which includes aus (pre-monsoon rice), aman (monsoon rice), lentil (Lens culinaris), and mungbean (Vigna radiata), was more profitable than the double or triple crop cropping systems, and farmers can easily follow this new system. This newly adopted cropping system may increase farm income while creating job opportunities, alleviating poverty, and ultimately creating positive changes in the farmers’ livelihoods.
Reports have shown that the four crop-based cropping systems increased the rice equivalent yield up to 20-46% and the gross margin up to 30-41% over the existing lentil–jute–aman rice and boro–fallow–aman rice systems. However, to acquire optimal performances in terms of yield, economic return, and soil health under the four crop-based cropping systems, the optimal fertilizer rate should be determined.
Various spatial and temporal aspects of soil health and the quality of a crop field greatly depend on the cropping systems followed in the field. If the cropping system contains exotic crops and intensive cultivation, nutrient depletion from the soil occurs quickly, and crop fields need more nutrients from external sources. Cropping systems were initially designed to obtain the maximum yield from agrosystems; however, sustainable and resilient agricultural production is now a major concern.
The goal of soil health maintenance is to ensure the cropping system’s long-term viability, high productivity, and environmental sustainability. Soil nutrients such as N, P, K, S, Zn, B, etc., play a key role in improving crop growth, yield, and quality and regulating the supply of nutrients to plants.
The intensive cultivation of crops using high-yielding varieties removes more plant nutrients from the soils; therefore, soil fertility is severely depleted. In addition, intensive cropping without adequate replenishment of the removed nutrients and nutrient loss through leaching, erosion, and gaseous emission cause the depletion of soil organic matter and fertility.
Therefore, soil fertility deterioration is the major concern in intensive cropping systems. To preserve and sustain soil fertility and ensure adequate crop yields in intensive cropping systems, proper fertilizer rate determination and management are required.
Additionally, the inclusion of leguminous crops in the cropping system increases soil fertility through biological nitrogen fixation and improves the soil structure. In addition, the incorporation of legume residues increases the organic matter in the soil, and food legumes also provide human and animal protein. It has been well recognized that a balanced application of macro- and micronutrients is required to ensure high individual crop yields and the system’s productivity.
The necessary correction of crop plant nutrition for an intensive cropping system is a routine task, as soil nutrient status varies regularly depending on crop growth, yield targets, crop type, and following plant nutrient management. However, the optimally balanced nutrient requirement in four crop-based intensive cropping systems has not been studied yet. Therefore, the present study was undertaken to modify the doses of fertilizers for the four crop-based cropping systems for the enhancement of productivity and sustainable soil fertility.
The productivity and nutrient uptake efficiency of the individual crop, as well as the four crop-based systems in this study, confirmed that current fertilizer recommendations or farmers’ fertilizer practices for three crop-based systems are not adequate. The increased fertilizer use by 25% of the recommended dose (125% RDF) was also economically more profitable with a cost-benefit ratio that is 26.8%, 4.4%, and 4.9% higher over the control, 100% RDF, and FP, respectively.
Revisions of farmers’ practices of fertilizer application based on soil test value (100%) and the increased rate of fertilizers (125%) maintained higher yields and improved soil fertility compared to current farmers’ practices or lower doses of nutrients.
The increments of soil organic C, total N, available P, K, S, Zn, and B concentrations in soils under 100% and 125% recommended fertilizer doses after two years of the study indicate that, for sustainable soil fertility management and for sustainably increasing cropping intensity, the fertilizer recommendation must be modified for the individual crop by using soil test values or by increasing fertilizer rates at least by 25% of the recommendation for the initial few years.
The cropping systems in the four crop-based systems were intensified by the inclusion of lentil and mungbean and it is expected that the use of these leguminous crops on a long-term basis in the systems will increase soil fertility as well as fertilizer use efficiency, which may help further decrease fertilizer requirements.
Read the study:
Quddus MA, Anwar MB, Alam MK, Ahmed R, Sarker KK, Islam MA, Islam MT, Kobeasy MI, Gaber A, Ahmed S. (2022) Modification of Nutrient Requirements for a Four Crop-Based Cropping System to Increase System Productivity, Maintain Soil Fertility, and Achieve Sustainable Intensification. Sustainability. 14(12):7194.
