1. Replace just as much water as the plants have used and you'll get maximum yield with minimum water.
结构分析：句子的框架是 Replace...water...and you'll get maximum yield with minimum water。 Replace...and you'll get...,像这种 do something and you will...的句型往往暗含一种条件关系，相当于 If you..., you'll...。yield 在这里意为“产量”。
2. He is a soil physicist at Texas A&M University in Lubbock who is working with Evett, other scientists at Texas A&M University, and Dynamax, Inc, of Houston, Texas.
结构分析：句子的框架是 He is a soil physicist...who is working with Evett, other scientists...。此句的主干为一简单句型：He is a soil physicist...，但后面还跟有 who 引导的定语从句，修饰主语 He; 另外注意，other scientists 并不是 Evett 的同位语，因为两者首先在单复数上就不一致，它与 Evett 并列跟在 with 后。
3. The measurement is done with stainless steel probes placed in the ground at varying depths, from a few inches down to several feet.
结构分析：句子的框架是 The measurement is done with...probes placed in the ground...。此句的主干为一简单句型：The measurement is done with..., with 引导的介词短语作方式状语，在这个状语中又有一过去分词结构 placed...作定语；介词短语 from a few inches down to several feet 是对 varying depths 的进一步解释。
4. The longer it takes for the pulse to travel through the probe, the more soil water.
结构分析：句子的框架是 The longer...the more...，翻译为“越……越……”。

He says the tests have been very successful so far and that automation could be used with other crops and other irrigation systems.
结构分析：句子的框架是 He says the tests have been...and that automation could be used...。该句的主干是 He says+宾语从句 1 +and+宾语从句 2，其中第二个宾语从句是个被动句。