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- Author or Editor: J. H. Edwards x
Total nutrient content, uptake rates, and distribution were determined for seedlings of peach [Prunus persica (L.) Batsch] grown in nutrient solutions containing 0, 222, 666, and 2000 µ m Al. Generally, total nutrient content decreased in the peach seedling organs as Al concentration increased. The responses obtained with increased Al concentration were linear with some nutrients and curvilinear with others and varied with plant organ. As Al concentration increased, the uptake rates for P, Ca, Mg, Zn, and Mn decreased but those for K and Fe increased. Aluminum did not alter the translocation of most nutrients; however, a greater percentage of the absorbed Ca accumulated in the leaves than in the roots or stems. Thus, aluminum toxicity in peaches may be related to a reduction in Ca uptake rate and not to inhibition in translocation of Ca.
Blue color development in Hydrangea macrophylla is usually accomplished by applying Al as an alum drench. Drenches are applied during forcing 10–14 days after transplanting at a rate of 17,500 mg·L-1. Cultivars Blue Wave and Nikko Blue were used to evaluate if the Al contained in waste paper can provide the necessary Al for blue flower development. Two waste paper forms, pelletized and crumble, were used as surface mulches and as media amendments. The amendments were incorporated into the media at transplanting and mulches were applied either at transplanting or 28 days later. Alum drenching was initiated at transplanting as a control. Leachates were collected weekly using the VTEM. Total Al, electrical conductivity, and pH were determined on all samples. All waste paper treatments resulted in pink flowers in both cultivars. Leachate pH, from plants in this test, was >6.5. Aluminum concentration was greater than the 15 mg·L-1 Al needed for blue color development in flowers, but Al concentration decreased with time. Control of pH at the waste paper surface and in the media is critical for increasing the availability of labile Al for uptake by hydrangea.
‘Redglobe’ peaches (Prunus persica (L.) Batsch) were grown under drip irrigation and no irrigation, with and without fumigation with 1,2–dibromo–3–chloropropane (DBCP). The irrigation treatments were 1) nonirrigated, 2) irrigated until harvest, 3) irrigated from harvest to dormancy, 4) irrigated all season. Fumigation increased trunk cross-sectional area by 18 cm2, and when postharvest water was applied the increase was 25 cm2 at the end of 1978. Irrigation increased marketable yields of fresh peaches from 3.6 to 7.4 MT/ha (62-150 bu/acre) in 1977. In 1978, fumigation did not increase yields unless preharvest water was applied; then, yields were increased from 12.1 to 17.2 MT/ha (232-357 bu/acre). Fumigation apparently increased water use as indicated by the increased rate of controlled water application. Fumigation reduced populations of Macroposthonia xenoplax (Raski) DeGrisse and Loof, from a range of 30-400 to a range of 1-30 nematodes/150 cm3 of soil.
Excessive moisture is a problem in evaluating recycled paper products as mulch to replace other common mulch materials and in landscape and container uses. To isolate the water associated with soil and/or media, two recycled paper products, pellets or crumble, were used as mulches in trade gallon containers in a greenhouse. Pine bark, pellets, and crumble needed to obtain standard mulch depth were enclosed in plastic mesh. These mulches were placed in containers that contained 1 kg of a 7 pine bark : 1 sand media. All containers were saturated with tap water for 24 hours. Mulches were placed on each container and allowed to drain for 1 hour. Weights of media, mulch, and media and mulch were obtained every 24 hours for a total of 312 hours. Water content of the media was not influenced by any of the mulch treatments. Water content of the paper products was increased by a factor of two. Pine bark mulch water content was zero 96 hours after an initial dry down cycle began, while the water content of pellet and crumble were 100 and 90 cm of water. Total water content of the media plus the mulch was increased by 30% to 35% when compared to pine bark mulch alone. However, the increase was associated with the water content of the waste paper mulch.
Selected fertilizer treatments were applied to vinca (Catharanthus roseus `Peppermint Cooler') in the landscape to determine their effect on growth and nutrient leaching. In plots 0.9 m × 2.3 m, inorganic fertilizers were applied as either a single application of 4.9 g N/m2 pre-plant, or a split application with 4.9 g N/m2 applied pre-plant followed by application of 2.45 g N/m2 at 8 and 12 weeks after planting (WAP). Inorganic fertilizers included 15N–0P–12.6K granular fertilizer, Osmocote 14N–6.0P–11.6K, and Osmocote 17N–3.0P–10.1K controlled-release fertilizers. Three different organically based fertilizers were applied pre-plant and were composed of recycled newspaper amended with animal manures (chicken, beef cattle, or dairy) and adjusted with (NH4)2SO4 to achieve C:N ratios of either 20:1 or 30:1. A standard industry treatment of 13N–5.6P–10.9K (4.9 g N/m2) incorporated pre-plant and 17N–3.0P–10.1K (4.9 g N/m2) topdressed post-plant was also included. Leachates, collected with lysimeters, from inorganic fertilizer plots had lower levels of total N (NO3 – + NH4 +) compared to organically based fertilizer plots through 8 WAP. Of the inorganic fertilizer plots, those receiving 15N–0P–12.6K granular fertilizer had higher total N levels at 1, 2, and 4 WAP than other inorganic fertilizer plots. Total N in leachates declined over the study and by 12 WAP were similar among all treatments. Vinca treated with organically based fertilizers (C:N 20:1) had the highest foliar color ratings through 8 WAP; however, color ratings declined thereafter and by 16 WAP had the lowest ratings. Plants treated with organically based fertilizers had greater shoot dry weights 20 WAP and larger growth indices 8 and 20 WAP.
Recycled paper pellets in the bottom of containers were evaluated for retention of N from container leachate. `Formosa' azalea were transplanted on 15 Apr. in 2.8-L containers in a pine bark/peat substrate (3:1; v/v). Treatments included paper (0 or 2.5 cm depth) in the bottom of containers and two rates of Osmocote 18–6–12 (0.68 kg or 1.36 kg N/yd3). Immediately after transplanting, plants were topdressed with 3.2 g of 12–4–6 fertilizer. Data collected included leachate samples every 2 weeks for NO3-N and NH4-N levels and destructive sampling every 4 weeks for shoot dry weight, foliar N, and total paper N. Nitrate-N and NH4-N leachate concentrations were reduced with the 0.68 kg N/yd3 fertilizer rate and with paper. For example, 28 days after planting (DAP) NO3-N leachate concentrations were reduced 36% with the 0.68 kg N/yd3 fertilizer rate and 46% with paper in the bottom of containers. NH4-N in the leachates was reduced 53% with the 0.68 kg N/yd3 fertilizer rate and 59% with paper. Azalea shoot dry weight was not affected by paper or fertilizer rate up to 112 DAP; however, as the study progressed, plants with paper in the bottom of containers grew larger than plants in no paper treatments (29% at 168 DAP, 31% at 196 DAP). Total N absorbed by paper was not affected by fertilizer rate, and peaked at 168 DAP [980 (0.68 kg N/yd3) to 1066 (1.36 kg N/yd3) mg per container, or 41% – 28% of applied N], after which it began to decline. This decline in paper N was associated with greater growth of azalea with paper.
Two experiments were conducted to evaluate recycled newspaper products as nutrient filters in the bottom of containers. In Expt. 1 with poinsettia, Euphorbia pulcherrima Willd. ex Klotzsch `Glory', three paper products were evaluated: ground paper, paper crumble, and paper pellets; each placed 2 or 3 cm deep in the bottom of containers, so that drainage holes were covered. Leachate samples were collected at the first irrigation after each liquid fertilization. Nitrate (NO3 --N) and ammonium (NH4 +-N) leachate concentrations were reduced up to 84% with recycled paper pellets, compared to the control (no paper). Recycled paper retained up to 732 mg of nitrogen (N) per container (paper pellets 3 cm deep). Shoot dry weight was reduced with paper pellets but was not affected by ground paper or paper crumble. In Expt. 2, `Freedom Red' poinsettias were grown with either single weekly applications of 500 mg·L-1 N from Peter's 20N-4.3P-16.6K, or 200 mg·L-1 N at each irrigation (2 or 3 times a week, as needed). Recycled paper treatments included paper crumble or paper pellets placed 2.5 cm deep in the bottom of containers, and a control without paper. Leachate NO3 --N and NH4 +-N concentrations were reduced up to 100% and 94%, respectively, 6 days after planting (DAP), and up to 57% and 50%, respectively, 25 DAP with paper crumble compared to nonpaper control. Paper pellets in the bottom of containers retained up to 776 mg N per container. Poinsettia shoot dry weight was lowest with paper pellets in the bottom of containers and continuous fertilization.
Nitrogen rate and in-row plant spacing significantly influenced yields of mechanically harvested red Tabasco (Capsicum frutescens L.) pepper. Red pepper yields increased with an increase in N rate from 0 to 112 kg N/ha, and a decrease in in-row plant spacing from 81 to 10 cm. The percentage of machine harvested red pepper in relation to green and orange fruit removal was enhanced with 20 cm in-row spaced plants. Tabasco plant height increased with an increase in N rate from 0 to 112 kg N/ha, while plant diameter decreased with a decrease in in-row spacing from 81 to 10 cm. Conventionally spaced (81 cm in-row spacing) Tabasco plants were damaged substantially more during mechanical harvesting than 10 cm in-row spaced plants. Early season leaf-petiole tissue N concentrations had higher correlations with red pepper yields than did late season tissue N concentrations. Multiple harvests of red Tabasco pepper with a flail-type machine produced yields similar to those obtained with hand harvesting.
‘Redglobe’ peaches [Prunus persica (L.) Batsch] were grown under drip irrigation. Applications of NH4NO3 through the irrigation system were compared with broadcast applications. Soil pH, where NH4NO3 was applied through the irrigation system, decreased in the top 30 cm from 6.2 to 3.7 pH in the zone wetted by emitters that had been in place for 2 years, and from 6.2 to 4.5 pH in the zone where emitters had been in place for 6 months. Aluminum concentration in wetted zones increased from 0.01 to 1.45 meq/100 g of soil after 2 years and from 0.02 to 0.73 meq/100 g of soil after 6 months of NH4NO3 application through drip irrigation. Soil Ca and Mg concentrations were reduced in both wetted zones, but the greatest decrease occurred in the 2-year emitter site. The addition of NH4NO3 in the irrigation water substantially reduced root growth in the vicinity of the emitters, irrigation water application, and fruit yield, because of the high A1 concentration in the wetted zone.
Two experiments were conducted with pansy (Viola ×wittrockiana Gams `Bingo Yello') to determine the relationship between foliar nitrogen (% of dry weight) (FN) and either sap nitrate concentration (SN) in petioles or SPAD readings of foliage. FN was highly correlated to SN throughout both experiments (r = 0.80 to 0.91). FN was poorly correlated to SPAD readings early in both experiments (r = 0.54 to 0.65), but more highly correlated later when visual symptoms of N deficiency were apparent (r = 0.84 to 0.90). SN determined with the Cardy sap nitrate meter was a reliable predictor of FN in pansy, while SPAD readings were only reliable after symptoms of N deficiency were visually evident. FN can be predicted with SN using the following equation: log(SN) = 0.47*FN + 1.6 [r 2 = 0.80, n = 132]. Growers and landscape professionals can use SN readings to predict FN levels in pansy, and thus rapidly and accurately diagnose the N status of their crop.