International Year of Pulses
Celebration of 2016 as the International Year of Pulses is timely and important because of the important role that pulses play in enhancing soil health and improving human nutrition and wellbeing.
Pulses and Soil Health:
Soil health refers to its capacity to function as a dynamic and biologically-active entity that affects health of plants, animals and people and generate numerous ecosystem services of relevance to human and nature conservancy. Important among these ecosystem services are net primary productivity, food and nutritional security, biodiversity, water purification and renewability, carbon sequestration and moderation of gaseous emissions elemental cycling etc. Pulses impact soil health through their impacts on soil physical, chemical and biological properties. Incorporating pulses in crop rotation impacts soil physical properties including aggregation (especially percentage of macro aggregates > 3mm) and soil structure because of the glomalin contents, soil tilth and formation of biophores, enhanced porosity and favorable pore size distribution, and improved aeration and gaseous exchange. Pulses also affect soil chemical properties especially soil fertility through biological nitrogen fixation(BNF), soil organic carbon (SOC)content through input of a high quality residues with a narrow C:N ratio and changes in soil PH.The rate of BNF(Kg N/ha) under pulses can range from 30-120 for lentil, 20-100 for chickpea, 5-70 for dry bean and 80-160 for faba bean. Thus, C:N ratio of crop residues for chickpea and lentils is about 17 compared with that of 40 for oilseed crops and more than 30 for wheat. The C:N ratio of some non-leguminous crops can be >100.Biologically,pulses can also impact microbial biomass carbon (MBC), soil enzyme and accentuate activity and species diversity of soil biota including macro biota (e.g. earthworms and termites) and enhance disease-suppressive attributes of the soil.
Improvements of soil structure by pulses can improve the water use efficiency of the following crops. Experiments conducted in Queensland, Australia documented the water use efficiency (kg/ha.mm ) of sorghum of 5-7 when sorghum followed sorghum compared with 10-14 when sorghum followed mungbean and 11 –13 after lab lab. Increase in WUE is due to better water conservation in the root zone and avoidance of drought.
Adaptation and Mitigation of Climate Change:
Through their impacts on soil health and functionality, pulses enhance adaptation and mitigation of climate change. Growing pulses can decrease gaseous emissions ( e.g.,nitrous oxide) by reducing input of nitrogenous fertilizers, improving soil structure and tilth, conserving water and soil, and increasing crop diversity thereby reducing inputs of herbicides and pesticides. Pulses can also increase the rate of soil carbon sequestration by increasing MBC and contributing N-rich residues. The measured rates of SOC in soils of India range from 300 to 400 kg.C/ha.yr. However, inoculating pulse crops with rhizobia can increase emission of nitrous oxide from soil.
Global Food and Nutritional Security:
In addition to about 800 million people who are prone to hunger, there are about 2 billion who suffer from hidden hunger and malnutrition. As an important source of protein and minerals, including pulses in diet is an important strategy to alleviate hunger and improve human health and wellbeing. Substituting pulses for animal-based protein can save a lot of land and grains to feed the growing population of the world.
Pulses are important to soil, environment and human health. Designation of 2016 as the UN International year of Pulses will enhance awareness about the importance of pulses.
Sincerely
Rattan Lal
Distinguished University Professor of Soil Science
Director, Carbon Management and Sequestration Center
President Elect, International Union of Soil Sciences
Adjunct Professor, University of Iceland
The Ohio State University
Columbus,OH 43210,USA
Phone:614-292-9069
Fax: 614-292-7432
E-Mail:[email protected]
Rattan Lal