Agronomic Assessment of Corn Silage Forage Production in Buckeye, and Casa Grande Arizona: Part of the Arizona Dairy Forage Initiative

Abstract

Production of high-quality forage crops through profitable and sustainable means is extremely important to dairy operations in Arizona. A significant limiting factor to achieving this efficiency is proper irrigation water management. A study was conducted in order to assess the irrigation efficiency in two corn silage fields in Arizona. Results from this study indicate that fields of interest can still significantly improve water management primarily through proper leveling of the field. The differences observed in penetration of water can negatively affect overall crop health and thus have an effect on harvest yield. The results indicate some water ponding is occurring in the middle of field 1 (Buckeye), however; the differences in centibar reading contrast greater in the field 2(Casa Grande). Further data incorporating yield parameters is pending.


Objective

This research assesses the efficiency of flood irrigation systems being implemented for corn silage forage production through installation of irrometer sensors at different depths and locations in corn fields of interest.


Hypothesis

If the fields being evaluated are leveled properly then we will see a mostly consistent centibar reading between different posts and depths, whereas if the fields aren't leveled properly then the readings throughout the field will vary significantly and some areas of the field will receive too much water while other receive too little water.



Methods

15 WATERMARK sensors (WS; Irrometer Company Inc., Riverside, CA) were installed per field at 5 different locations in each field with each location having an irrometer device at 20 cm, 46 cm, and 102 cm of depth along and a temperature probe placed with the 46 cm WS. A current is applied to the WS to obtain a resistance value that is then correlated to a WATERMARK monitor as Centibars (kilopascals) of soil water tension. Data was collected over a 53 day period then analyzed using the PROC MIXED (SAS Institute 9.4, Cary, NC, USA). Independent variables included post, depth and their respective interactions. When significant effects were observed (P<0.05), differences between the means were evaluated.


Table 1. Post 1 is closest to the irrigation ports while post 5 is farthest. Lower centibar readings indicate more plant available water.

Outcomes

These data indicate that both of these fields can still significantly improve levelness in order to achieve a consistent irrigation and efficient use of water. The differences in penetration of water can negatively affect overall crop health and thus have an effect on harvest yield. The results from the Buckeye field indicate some water ponding is occurring in the middle of the field, however; the differences in centibar reading contrast to a greater extent in the Casa Grande field. The high centibar reading at the posts closest to the water source indicate that the slope of the field is too extreme, which is causing the water to run off too fast and pool towards the end of the field.


Figure 1. Post 1 is closest to irrigation ports while post 5 is furthest. Taller bars indicate increased water tension and less available water. Superscripts (a-d) indicate differences between the means at (P<0.05)
Figure 2. Post 1 is closest to irrigation ports while post 5 is furthest. Taller bars indicate increased water tension and less available water. All means differ at (P<0.05)

Blase Evancho

Assistant-in-Extension Pima & Pinal Counties

Blase is an agronomist working on field crops with a keen interest in alternative cropping systems. His primary projects include guayule commercialization, cotton variety testing, cotton heat stress, alfalfa heat stress and plant pathogen suppression.

Pablo Grijalva, University of Arizona - Graduate Research Assistant

Duarte Diaz, Dairy Extension Specialist, Lead Dairy Forage Initiative

Mike Ottman, Extension Specialist Agronomy, Lead Dairy Forage Initiative

Pedro Andrade, Associate Specialist, Agricultural-Biosystems Engineering

Randy Norton, Director - Graham County Extension; Resident Director - Safford Agricultural Center; Area Associate Agent - Agriculture

Ayman Mostafa, Associate Area Agent, Agriculture; Associate Regional Specialist, Entomology