bioplastics containing soy could allow for reduced fertilizer inputs during production of plants with short production cycles. To test this hypothesis, our objectives were to grow a common greenhouse-grown crop in various soy-composite biocontainers under a
Kenneth G. McCabe, James A. Schrader, Christopher J. Currey, David Grewell, and William R. Graves
T.L. Schultz and U.K. Schuch
Nitrate nitrogen is becoming a major pollutant in much of our nation's water supply. High levels of nitrate runoff are commonly found to occur from intense agricultural areas such as container nurseries. The objective of this study was to investigate combinations of liquid fertilizer (LF) plus controlled-release fertilizer (CRF) that would both minimize nitrate runoff and provide nutrient levels for optimum growth of Ilex verticillata L. The experiment was established in 1998 at the Iowa State Univ. Horticulture Research Station, Ames. Six fertilizer treatments were arranged in a randomized block design with eight replications. Treatment combinations of liquid fertilizer (LF) and controlled-release fertilizer (CRF) were [LF (mg/L)/CRF (g)]: 90/0, 90/8.5, 90/17, 180/0, 180/8.5, 180/17 (Peter's Excel 21-5-20 and Osmocote 18-6-12, 9-month release, respectively). Analysis of nitrate leaching showed that in 12 out of 16 weeks, the 180 mg/L LF treatments resulted in twice the amount of nitrate leached compared to the 90 mg/L LF. In 3 out of 16 weeks, treatments containing 0 g CRF leached significantly less nitrate than those containing 17 g CRF. None of the treatments produced a difference in total dry weight or caliper of Ilex verticlillata L. This data suggests that plant growth remains similar over a range of fertilizer input and higher rates of applied LF result in higher nitrate leaching.
Youbin Zheng*, Thomas Graham, Stefan Richard, and Mike Dixon
Pot gerbera (Gerbera jamesonii Var. `Shogun') plants were subirrigated with one of four nutrient solutions (10, 25, 50, and 100% of full strength) in order to determine whether currently used commercial nutrient solution concentrations can be reduced without negative impact on crop production. Nutrient concentration levels did not affect leaf area, flower number and appearance, and plant total dry weight. There were no significant differences in leaf chlorophyll content between the plants that received the 50 and 100% strength nutrient solutions. It is concluded that nutrient solution concentrations typically used in commercial greenhouse, for pot gerbera production, can be safely reduced by at least 50% without adversely affecting crop production. Nutrients accumulated in the top section of the growth substrate under all treatment levels; however, no phytotoxic effect was observed. Fertilizer inputs were reduced in the 50%, 25%, and 10% treatments by 54%, 75%, and 90% respectively. After 4 weeks recirculating, the quality of the nutrient solutions was still within acceptable limits.
Shichao Wang, Zhujun Chen, Jun Man, and Jianbin Zhou
high ( Li et al., 2017 ; Shi et al., 2018 ). Therefore, excessive inputs of nutrients are still widely observed in vegetable production in China ( Cai et al., 2016 ; Liu et al., 2017 ; Zhao et al., 2017 ; Zhou, 2017 ). Such overuse of fertilizers
N.R. Rice, M.W. Smith, R.D. Eikenbary, D.C. Arnold, W.L. Tedders, B.W. Wood, G.G. Taylor, B.S. Landgraf, and G.E. Barlow
Annual legume ground covers were evaluated in pecan (Carya illinoinensis) orchards to supply nitrogen and increase beneficial arthropods. Treatments were established at two sites, each with 5 ha of a `Dixie' crimson clover (Trifolium incarnatum) /hairy, vetch (Vicia villosa) mixture and 5 ha of grass sod. Data indicated that the legume mixture supplied over 100 kg·ha-1 N to the pecan trees. Beneficial arthropods were greater in orchards with legume ground covers than in orchards with a grass groundcover. Lady beetles and green lacewings were the most important spring predators, and green lacewings were the most important fall predator. The Species distribution on the ground covers differed from that in the canopy. Coleomegilla maculata lengi, Hippodamia convergens and Coccinella septempunctata were the most abundant lady beetle species in the legume ground covers, and Olla v-nigrum, Cycloneda munda, and Hippodamia convergens were the most abundant species in the pecan canopies. Beneficial arthropods appeared to suppress injurious pecan aphids.
Pablo R. Hidalgo, Richard L. Harkess, and Frank Matta
Earthworm castings were evaluated to determine the effect of earthworm castings on growth of Poinsettia `Freedom Bright Red'. Castings derived from cow (CC), horse (HC), or sheep (SC) manure were combined with peatmoss at 1:0, 1:3, 1:1, 3:1, or 0:1 peat: castings (v/v). One plant was potted per 1.5-L container and were fertilized at 0, 50, 200, or 350 mg/L N in a RCB arrangement. Plant growth index at all fertilizer rates was greatest when grown in SC at 0:1, 1:3, and 1:1 and CC at 0:1 and 1:3 (peat: castings) ratios. For each of the three animal sources, no differences in growth index were observed among fertilizer rates when 100% castings was used as the substrate. Bract area was greatest on plants grown in SC at 1:0, 1:3, and 1:1 (peat: castings) ratios at all four fertilizer rates. Bract area on plants grown in CC at 0:1 and 1:3 (peat: castings) was less than SC, but better than CC at 1:1, 3:1, or 1:0 or any of the HC substrates. Plants grown in substrates with 75% or more castings all had similar bract area regardless of fertilizer rate. As castings in the substrate decreased, bract area increased as fertilizer rate increased. When fertilized at 0, 50, or 200 mg/liter N plant dry weight decreased as castings increased in the substrate. Fertilization at 350 mg/liter did not affect dry weight between substrates.
N. M. El-Hout
Band placement has been recognized as an effective strategy for improving P fertilizer-use efficiency on Histosols, which are often characterized as environmentally sensitive wetlands, and for reducing P loading of drainage waters from these soils. Recent studies indicate that crisphead lettuce (Lacruca sativa L.) yields can be optimized with a band-P rate one-third of that required with broadcast applications. However, such findings have not been verified in large production plots. Five field experiments were conducted between 1991 and 1993 to evaluate the response of crisphead lettuce produced commercially on Histosols to band P rates. Liquid P fertilizers were placed in lo-cm-wide strips, 8.5-cm below the seed at planting in rates ranging from 0 to 224 kg P ha-1. Lettuce yields increased significantly with P rate in all experiments. Irrespective of initial soil-test-P index, lettuce yields within each experiment were maximized with a band rate 54% of that required in a broadcast. The pooled data for all experiments showed a similar trend. These findings provided a means of making alternative band fertilizer recommendations by utilizing an existing preplant broadcast soil test.
Shichao Wang, Xinlu Bai, Jianbin Zhou, and Zhujun Chen
other half of the same greenhouse, where the farmer added water and fertilizer according to his experience (FP). The irrigation rate and fertilizer inputs for the different treatments for 2 years are given in Table 1 . Table 1. Irrigation rates and
Angela Y.Y. Kong, Cynthia Rosenzweig, and Joshua Arky
depleted, rooftop farms rely on external inputs to maintain their productivity. Nitrogen, a key nutrient, can be introduced through the sole or combined additions of synthetic fertilizers and organic amendments, such as composted animal manure, composted
Amaya Atucha, Ian A. Merwin, Chandra K. Purohit, and Michael G. Brown
. Estimating nutrient fluxes and requirements under different orchard systems is essential to produce high yields of marketable fruit while minimizing the loss of fertilizer in leaching or runoff and subsequent environmental contamination. Where nutrient inputs