India, renowned worldwide for its rich artistic heritage, mystically vibrant culture, and profound philosophical wisdom, has played a significant role in the evolution of global civilization. Through centuries, numerous advanced theories, skills, and innovations surface its scientific literature that has significantly influenced many other civilizations worldwide, even in the fields of mathematics and astronomy. However, one field that often goes unsung is ancient India's profound expertise in agricultural science and technology. The primary focus of this discourse will revolve around how ancient Indians mastered fertilization techniques without the aid of modern-day microscopes.

Agriculture, the backbone of Indian civilization, dates back to around 9000-7000 BC during the Neolithic era when the first farming settlements emerged with the domestication of crops such as barley and wheat. Ancient Indian agricultural science, with its meticulous and holistic approach, was bordering on avant-garde. The farmers were not just basic cultivators; they were pioneering agriculturists who understood crop management's nuanced aspects.

These agricultural savants' innovation lies in their understanding and practice of fertilization, a cornerstone of crop cultivation. Without modern tools or resources' availability, ancient Indians had intuitively discovered the utility of organic and inorganic matter as agents of fertilization.

Their meticulous understanding of nature and the environment helped them understand the benefits of recycling organic waste as manure to preserve the soil's fertility.

Ancient Indian literature, such as the "Krishi-Parashara" and the "Brihat Samhita," provided insightful details about using animal waste, plants, and ash as organic fertilizers. The texts even guide one on timing the application of such substances concerning seasons and climatic conditions. This emphasizes the ancient Indians' understanding of how seasonal and environmental conditions affect soil fertility.

The traditional method of composting was an intrinsic part of agriculture in ancient India, where decaying organic matter was broken down by microorganisms in the soil, producing nutrient-rich manure for the crops.

This method not only recycled waste but also ensured that the soil was replenished with vital nutrients enhancing its fertility cycle. They also innately understood the rotation of crops, maintaining soil fertility by growing different crops in the same field over a period.

It is fascinating to note that these techniques align multifold with modern agricultural sciences. The Indian ancient method of 'vermicomposting,' which involves breeding earthworms to speed up the composting process, is a highly efficient modern technique to prepare organic manure.  

Without the use of microscopes, ancient Indians mastered the understanding of soil microorganisms and their role in breaking down organic matter.

They developed agricultural manures using biological resources such as cow urine and dung, plant residues, and human waste. They acknowledged that different types of soils required different types of manures. They even used inorganic matter like ashes derived from burnt plant residues as potash.

In conclusion, the domain of ancient Indian innovations is colossal and often underrepresented. The mastery of fertilization without the use of modern-day microscopes showcases the age-old civilization's intuition and brilliance. The agricultural practices bore witness to India's scientific prowess and environmental consciousness way before it dominated global discourse.

This understanding and respect for the environment and ecology make ancient Indian agricultural science a model worth revisiting and imbibing. Their practices need to be recognized, acknowledged, and incorporated even today to ensure sustainable agriculture.