ISHS Acta Horticulturae 819: International Symposium on Growing Media 2007
A GRAVIMETRIC APPROACH TO REAL-TIME MONITORING OF SUBSTRATE WETNESS IN CONTAINER-GROWN NURSERY CROPS |
| Authors: | J.S. Owen, Jr., S.L. Warren, T.E. Bilderback |
| Keywords: | Cotoneaster dammeri 'Skogholm', water use, micro-irrigation, water monitoring, soilless media, clay, substrate amendment |
| Abstract:
Water management should be at the core of container nursery production. To increase water use efficiency, a better of understanding of how water is lost and subsequent hydration for soilless substrates is needed. Thus, the objective of this study was to monitor real-time daily substrate wetting and drying cycles as influenced by substrate and time of irrigation. To accomplish this objective a 2 (substrates) × 2 (irrigation timing) factorial study was conducted. Cotoneaster dammeri C.K. Schneid. ‘Skogholm’ (cotoneaster) was grown in two substrates consisting of aged (~1 yr) pine bark screened <1.25 cm and amended with a mineral aggregate (clay) (PBC) or coarse, washed builder’s sand (PBS) at 9% (by vol.) and irrigated with one of two irrigation timings (AM cyclic application where the total daily volume to maintain a 0.2 LF was divided equally into three applications and applied at 0100, 0400, and 0700 HR, and a PM cyclic application where the total volume to maintain a 0.2 LF was divided equally and applied at 1200, 1500, and 1800 HR). Total dry weight of cotoneaster was 18% greater when grown in PBC compared to cotoneaster grown in PBS, and the weight of cotoneaster irrigated in the PM was 40% greater compared to cotoneaster grown with AM irrigation. Maximum percentage of weight at container capacity (CC; maximum weight after saturation and drainage) for PBC decreased 0.8 and 0.6% per day for AM and PM irrigation timing, respectively. Minimum percentage of weight at CC also decreased 0.9 and 1.0% per day for AM and PM, respectively for the PBC. PBS behaved similarly. With AM irrigation, the first cycle was 100% water application efficient (WAE) for both substrates and accounted for 42% of the total water gain. During the second and third cycles of irrigation an average 34 ml (96% WAE) and 238 ml (79% WAE) of water were lost, respectively, which accounted for 20% of the total water applied. With PM irrigation, the first cycle was 100% efficient resulting in a 48% increase of the total water gain. In the second cycle, water application efficiency (WAE) decreased 6% resulting in 104 ml of water leached. The WAE of the third irrigation cycle was 88% with 199 ml water lost. Leachate lost in the second and third irrigation cycle accounted for 20% of the total water applied. | |
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