Agriculture is the livelihood of people in many natives. The modernization coming later on under many themes and also in many forms as well. What is clear is that the traditional agriculture in not only about livelihood, but also a system of living. The traditional agricultural system itself is sustainable in many forms socially, economically and culturally. When the modernisation introduced under the name of efficiency, productivity or sustainability, the traditional social system of the people challenged specially in the market economy due to many forces including globalisation..
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I would say it depends on what you mean by "modernization". Also "traditional" practises can be sustainable when well applied. https://www.jstor.org/stable/3985685?seq=1#page_scan_tab_contents
One of the key characteristics of modernisation is increased productivity. This increase in productivity helps ensure that production is able to continue. In fact were it not for this increase in productivity the world would be a very different place. Thomas Robert Malthus famously predicted that short-term gains in living standards would inevitably be undermined as human population growth outstripped food production, and thereby drive living standards back toward subsistence. This has not occurred as modernisation of agriculture has allowed this to happen. They key is how you define sustainable - if you are considering soil health then there is a movement towards farming practices such as conservation farming (at least that is what it is called in South Africa) that focuses on keeping ground cover on fields to build up soil and decrease the need for fertiliser. Some of the 'new' trends are related to some practices that were perviously the norm or some consider traditional. The key is building on knowledge and increasing productivity in manner that is able to continue in the long run.
I think the combination of modernized techniques with traditional concepts is more sustainable. We must not go through one system. When considering the Sri Lankan case, indigenous techniques such as organic farming, cascade system are sustainable environmentally friendly concepts but utilization of these methods not along with the modern agricultural methods is not sufficient to increase productivity level. Therefore, we should use both with proper understanding of hydrology, geology and soil science etc. for agriculture crop planting.
The question we need to address is modernization in Agriculture that do not overrun its benefits in reference to its effects in all aspects of Agriculture. How does it effect the soils, the people, the workers, climatic condensations, other living organizations and so on, not just an increase in productivity. Any imbalance with serious effects would mean a threat to sustainability in general. May be a mixture of traditional techniques and modernization is the answer, on this we need empirical evidence.
Sustainability in agriculture depenpends on inovations. The first step is prioritization of critical points of sustainability along the production chain, but a big challenge is technological, that is, we have to be able to offer innovations that solve problems in a sustainable way. Inovations can be get by new knowledge or tradidional knowledge.
We are usually advised to consider an integrated agricultural system. If we entirely depend on the modern agriculture (application of chemical fertilizers) by ignoring the organic farming, sustainability remains under growing challenge. Conversely, if we apply traditional agricultural system, we are friendly with the environmental health, but we could not feed the growing population. This could also be a future challenge as the poor could destruct the environment to feed their family. Hence, a new science of integrated agricultural system has been accepted as a right approach.
If modernization means substances that are toxic to the environment and human health, then it is a step backwards. See the Amazon in Brazil as the agricultural frontier expands for commodity exports while destroying the forest and indigenous peoples. Pardeep Singh