In situ Moisture Conservation

Major Areas :: Dryland Agriculture: In situ Moisture Conservation

IN-SITU MOISTURE CONSERVATION TECHNIQUES

Micro catchments:

1. Functions

To conserve insitu moisture and reduce soil loss
Circular basin of one meter diameter for level lands depending upon infiltration and rainfall
‘ V’ ditches of size 5m x 5m with trees planted centre and height according to the rainfall and slope of slopy lands
Saucer basins / semi circular bunds with 2m diameter to a height of 15-20cm across the slope

Broad beds and furrows:

Function	To control erosion and to conserve soil moisture in the soil during rainy days
General information	The broad bed and furrow system is laid within the field boundaries. The land levels taken and it is laid using either animal drawn or tractor drawn ridgers.
Cost	Approximate cost for laying beds and furrows is Rs. 1000/- per ha.
Salient features	Conserves soil moisture in dryland Controls sol erosion. Acts as a drainage channel during heavy rainy days.

Contour bund:

Function	To intercept the runoff flowing down the slope by an embankment.
General information	It helps to control runoff velocity. The embankment may be closed or open, surplus arrangements are provided whenever necessary.
Cost	Approximate cost for laying contour bund is Rs. 1500/- per ha.
Salient features	It can be adopted in light and medium textured soils. It can be laid upto 6% slopes. It helps to retain moisture in the field.

SPECIFICATION FOR BUND CROSS SECTION

Depth of soil (m)	Base width (m)	Top width (m)	Height (m)	Side slope (m)	Area cross section (sq.m)
Shallow soils (7.5 – 22.5 cm)	2.67	0.38	0.75	1.5 : 1	1.14
Medium soil (22.5 – 45 cm)	3.12	0.60	0.85	1.5 : 1	1.56
Medium deep soils	4.25	0.60	0.90	2 : 1	2.18

Situations for various bunding options:

Bunding options	Soil type	Rainfall (mm)	Slope (%)
Contour bund	Light soil	<600	>1.5
Graded bund	All soils	>600	1.5
Bench terraces	Deep soil	>1000	6.0
Graded boarder strip	Deep alfisol and related red soil	>800	>1.5

In-Situ Moisture Conservation Techniques

Soil Type	Rainfall	In-Situ Moisture Conservation Techniques
Red soil	Low	Dead furrow at 3-6 m interval
	Medium	Sowing on flat bed and riding later with eventual cultivation
	High	Graded border strips
Black soil	Low	Contour cultivation
	Medium	Dead furrows at 3-6 m interval
	High	Graded open furrow (0.2 to 0.3 m3) at 10 m interval across the slope

IMPROVING SOIL MOISTURE STORAGE

Addition of silt, clay, organic matter etc., increases field capacity and also raises wilting point to marginal increase in available moisture holding capacity.