Introduction
The maximum damage to the ecology is caused by a combination of factors, including the use of fertilizers in agriculture, overharvesting, and the introduction of new alien species. Each of these factors contributes to the degradation of the environment in different ways.

Fertilizers in Agriculture
- Fertilizers are chemicals that are used to enhance the growth of crops by providing essential nutrients.
- However, the excessive use of fertilizers can have detrimental effects on the environment.
- When fertilizers are applied in large quantities, they can leach into nearby water bodies, causing water pollution.
- This pollution can lead to the eutrophication of rivers, lakes, and other aquatic ecosystems, resulting in the depletion of oxygen and the death of aquatic organisms.
- Additionally, the runoff of fertilizers into water bodies can also contribute to the growth of harmful algal blooms, which can further harm aquatic life.

Overharvesting
- Overharvesting refers to the excessive extraction of natural resources beyond their sustainable limits.
- This practice affects various ecosystems, including forests, fisheries, and wildlife habitats.
- Overharvesting of trees can lead to deforestation, which results in the loss of biodiversity and habitat destruction for many species.
- Overfishing can deplete fish populations, disrupt marine food chains, and negatively impact the livelihoods of fishing communities.
- Overhunting can drive certain animal species to extinction or push them towards endangerment, disrupting ecological balance.

New Alien Species
- The introduction of new alien species, also known as invasive species, can have severe ecological impacts.
- These species are non-native to the ecosystem and can outcompete native species for resources, disrupt food chains, and alter habitats.
- Invasive species often lack natural predators or diseases that control their populations, allowing them to multiply rapidly and dominate ecosystems.
- The presence of invasive species can result in the decline or extinction of native species, leading to a loss of biodiversity.
- Additionally, invasive species can also impact agricultural productivity, as they can damage crops and spread diseases.

Conclusion
All the factors mentioned - the use of fertilizers in agriculture, overharvesting, and the introduction of new alien species - contribute significantly to the damage inflicted on the ecology. Each of these factors has its specific set of negative impacts on the environment, including water pollution, deforestation, loss of biodiversity, and disruption of ecosystems. It is crucial to address these issues through sustainable practices and conservation efforts to minimize the damage to the ecology and ensure the long-term health of our planet.