Em4885 irrigation management practices to protect ground water
Em4885 irrigation management practices to protect ground water
Em4885 irrigation management practices to protect ground water
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4 CHAPTER<br />
IP 2.02.05 - Install a Suitable Field Gradient Using Laser-Controlled<br />
Landgrading Where Topsoil Depth Allows<br />
Objective<br />
Ensure an appropriate grade for the field length and soil characteristics in order <strong>to</strong> use<br />
surface <strong>irrigation</strong> systems efficiently.<br />
Description<br />
Efficient surface <strong>irrigation</strong> requires the right combination of flow, field slope, furrow/<br />
border strip length, and soil characteristics. A limiting fac<strong>to</strong>r may be <strong>to</strong>o steep or <strong>to</strong>o flat<br />
a field gradient in relation <strong>to</strong> the soil characteristics. If <strong>to</strong>psoil depth allows, make sure<br />
that an appropriate gradient is installed.<br />
SCS National Practices 464 and 466 address land grading and smoothing.<br />
IP 2.02.06 - Irrigate a Field in Two Cycles, One Cycle With Water<br />
in the Compacted Furrows, One in the Uncompacted Furrows<br />
Objective<br />
Improve cross-row uniformity in a manner that is easy for labor <strong>to</strong> implement - by using<br />
two, or more, combinations of flow rate and set time in separate cycles of <strong>irrigation</strong><br />
through a field.<br />
Description<br />
Some furrows will be compacted by trac<strong>to</strong>r traffic and some will not under normal<br />
conditions with annual crops. Thus, adjacent furrows may have different infiltration rates.<br />
These different infiltration rates should indicate different <strong>management</strong> strategies <strong>to</strong> achieve<br />
the same results, correct amounts of <strong>water</strong> infiltrated with good uniformity. This means<br />
shorter sets with larger stream sizes used in uncompacted furrows versus longer sets with<br />
smaller stream sizes in compacted furrows. This can be difficult and confusing for labor<br />
<strong>to</strong> accomplish if the field is irrigated normally, running every furrow with <strong>water</strong> in the<br />
same <strong>irrigation</strong> cycle.<br />
This Practice is <strong>to</strong> irrigate the field in two cycles. The first cycle runs <strong>water</strong> only in the<br />
compacted furrows using a single combination of furrow flow and set time. Then as all<br />
compacted furrows in the field are finished, another <strong>irrigation</strong> cycle is immediately started<br />
with <strong>water</strong> run in the uncompacted furrows. Again there will be a single, albeit different,<br />
strategy (probably larger flows for shorter sets) in use.<br />
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