Understanding Black Soil's Moisture Properties

Black soil is known for certain unique properties, particularly concerning how it handles moisture. These characteristics significantly influence its physical state and suitability for agriculture.

Moisture Absorption and Retention in Black Soil

Black soil, also known as Regur soil, is typically clayey in nature. This clayey texture gives it a high capacity to hold moisture. When it rains or the soil gets wet, it absorbs water slowly but can retain it for a very long time compared to other soil types like sandy soil. This slow absorption means it takes time for the soil to get completely saturated, but once saturated, it stays moist for prolonged periods, even during dry spells.

The Phenomenon of Cracking

Conversely, when black soil starts to dry out after being wet, it loses moisture slowly. As it loses moisture, the soil particles shrink, causing the soil to develop wide cracks. These cracks can be quite deep and prominent. This cracking is a direct result of the expansion and contraction of the clay minerals in the soil as they absorb and lose moisture.

What is Self-Ploughing?

The question asks for the character of this slow absorption and loss of moisture that retains moisture for a long time. This property directly leads to the formation of cracks when the soil dries. This cracking action, which happens naturally due to the soil's inherent characteristics, is often referred to as "self-ploughing". The cracks effectively break up the soil clods and aerate the soil, similar to how mechanical ploughing works. Thus, the slow moisture dynamics leading to cracking is the characteristic associated with the term self-ploughing.

Analyzing the Options

Let's look at the other options to understand why they are not the correct answer in this context:

• Soil degradation: This refers to the decline in the overall quality of soil, making it less fertile or productive. While poor management can lead to black soil degradation, the term doesn't describe the natural moisture absorption/retention and cracking property itself.
• Soil erosion: This is the process where soil is worn away or transported by natural forces like wind or water. Black soil can be susceptible to erosion, but the term erosion does not describe its moisture-related expansion, contraction, or cracking.
• Soil conservation: This refers to practices used to protect soil from erosion and degradation and maintain its health and fertility. It's a practice undertaken by humans, not an inherent characteristic of the soil's moisture dynamics.
• Self-ploughing: As explained, this term precisely describes the natural cracking that occurs in black soil due to its slow moisture absorption and retention properties, mimicking the effect of ploughing.

Therefore, the characteristic of black soil's slow absorption and loss of moisture, which retains moisture for a very long time and leads to cracking, is related to the phenomenon known as self-ploughing.

Revision Table: Black Soil Properties

Additional Information about Black Soil

Black soils are typically formed from volcanic rocks (basalt). They are rich in minerals like calcium carbonate, magnesium, potash, and lime. They are generally poor in phosphoric content. Black soils are very fertile and are ideal for growing crops like cotton, sugarcane, jowar, rice, and wheat. They are widely found in the Deccan Trap region, covering parts of Maharashtra, Madhya Pradesh, Gujarat, Andhra Pradesh, and Tamil Nadu.

The self-ploughing characteristic helps in aeration of the soil and makes it easier to cultivate after the first rain showers, as the cracks swell shut and the soil becomes workable.