Small Water Cycle and Soil Water Capacity
Author: Klaus Mager Issue: 2023-02-01
Small Water Cycle and Soil Water Capacity
by Klaus Mager
[Ed. note: ChatGPT is a new large language model which is focused on writing statistically plausible, but not necessarily factual, conversational answers to questions. Here you can see Klaus doing an experiment with ChatGPT, to synthesize general explanations about a topic in which he is interested. You will also note that Klaus does separate fact-checking with references, and uses his own judgement about what ChatGPT wrote.]
I thought to test my new ChatGPT to see what comes up about water and in particular the small water cycle.
Question: What is the Small Water Cycle
ChatGPT: The small water cycle, also known as the soil water cycle or the pedological water cycle, refers to the movement of water through the soil. This cycle starts when precipitation (rain or snow) infiltrates the soil, and then a portion of this water is taken up by plant roots and transpired into the atmosphere through the process of transpiration. The remaining water continues to move through the soil, either being taken up by plant roots or percolating deeper into the soil profile, eventually reaching groundwater aquifers.
The small water cycle is a critical component of the larger water cycle, as it helps to regulate the water balance in an ecosystem and supports plant growth and survival. The organic matter content in the soil also plays an important role in the small water cycle, as it helps to retain moisture in the soil, increasing the soil's water-holding capacity. The small water cycle is also important for water quality, as it can help filter and clean water as it moves through the soil.
Question: How much organic carbon is stored in healthy soil?
ChatGPT: The amount of organic carbon stored in healthy soil can vary widely depending on factors such as climate, soil type, and land use history. On average, healthy soils can contain between 2% and 8% organic carbon, but some soil types can contain up to 10% or more. This can represent a significant pool of carbon, with some estimates suggesting that soils contain more carbon than all the vegetation and the atmosphere combined.
Question: How much water can the soil hold, and how is that linked to soil organic carbon?
ChatGPT: Soil can hold varying amounts of water depending on its texture, structure, and organic matter content. Soils with high organic matter content can hold more water compared to those with low organic matter content due to its ability to absorb and retain water. Organic matter in soil acts like a sponge, holding onto water and releasing it gradually to plants. Soil organic carbon is directly linked to the soil's water-holding capacity, as higher organic matter content usually means higher organic carbon content, and vice versa.
The exact amount of additional water that soil can hold per 1% increase in soil organic carbon content is not well established, but research has shown that increasing soil organic carbon content can significantly improve soil water-holding capacity. Soils with higher organic carbon content can hold more water, reducing the need for irrigation and increasing drought tolerance for plants. However, the amount of water held per 1% increase in organic carbon content can vary greatly depending on soil type, climate, and other factors.
[back to Klaus]
When it comes to additional water holding capacity per 1% of SOM, the numbers ChatGPT generated are all over the place. The number I got from the Soil Health Institute was between 18-24k gals / acre. Here are a couple of articles as reference:
The Connection between Soil Organic Matter and Soil Water
The Small Water Cycle & Global Warming
So there are a lot of moving parts, but what seems to be very important is a) the small water cycle, and b) the infiltration of water into aquifers and watersheds. Depleted soil cannot absorb the water, it runs off taking top soil with it.
Overall a pretty accurate feedback, writing useful first copy.
Related:
- Klaus Mager (author)
- 2023 (year)
- Topics: Climate and Environment, Regenerative Systems and Agriculture