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Thomas A. Obreza and Jerry B. Sartain

cost and stringent environmental regulation, these industries have a critical need to improve nitrogen (N) and phosphorous (P) fertilizer use efficiency to remain sustainable. Plant nutrient management is intensive when producing high

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Diana Devereaux and Raul I. Cabrera

High levels of N are often used to produce a vigorous plant that is also aesthetically pleasing to the purchaser. Environmental concerns with the overuse of N raise the need to find the minimum N requirements necessary to produce a salable plant. Ilex opaca and Lagerstroemia indica plants growing in 1.5-gal containers were irrigated with nutrient solutions containing N concentrations of: 15, 30, 60, 120, 210, and 300 mg N/liter. After 4 months, data indicate that using solutions >60 mg N/liter for both plant species results in leachates with N concentrations higher than those in the applied solutions. Nitrogen leaching losses increased with applied N, ranging from ≈15% to 50% for the low and high treatments, respectively. Chlorophyll readings of leaf tissue were not significantly different for plants of both species receiving N solutions higher than 60 mg·liter–1. These results indicate that N levels lower than those typically used for production of these woody ornamentals will still produce salable plants while increasing N fertilizer-use efficiency.

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Laura L. Van Eerd and Kelsey A. O'Reilly

rates consistently produced lower fertilizer use efficiencies than low and medium rates ( Habtegebrial et al., 2007 ; Nissen and Wander, 2003 ; Van Eerd, 2007 ). Table 6. Nitrogen use efficiency indices of machine-harvested cucumbers. z Standardized N

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C.A. Sanchez, S. Swanson and P.S. Porter

Five field experiments were conducted from 1986 to 1989 to compare broadcast and band P fertilization of crisphead lettuce (Lactuca sativa L.) on Histosols. Rates of P were 0, 50, 100, 200, and 300 kg P/ha applied broadcast or banded. Broadcast P was surface-applied and disked into the soil 1 day before bedding and planting. Banded P was placed in strips 8 cm wide, 5 cm below the lettuce seeds at planting. Lettuce yields were significantly(P < 0.01) increased by P rate in all experiments. However, significant rate-by -placement interactions indicated that response of lettuce to P varied by placement. Lettuce yields were generally optimized with a band P rate one-third of that required with broadcast placement. Analysis of soil samples collected in the lettuce bed after fertilization indicated that banded P increased available P in the lettuce root zone compared to broadcast fertilization. Lettuce leaf P concentration increased with P rate and generally was greater when P was banded. The critical concentration of P in lettuce leaf tissue at the six- to eight-leaf stage was 0.37%. Banding P fertilizer did not reduce the availability of other essential nutrients, as indicated by tissue analysis.

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Eric J. Hanson and G. Stanley Howell

Mature `Concord' vines (Vitis labrusca L.) were excavated at 2- to 4-week intervals through the season to study seasonal changes in vine N concentration. Vine N content began increasing 2 weeks after budbreak, increased most rapidly from mid-May to mid-July, and declined between fruit maturation and the beginning of leaf senescence. Vine N content was lowest at budbreak (18 g) and maximum at fruit maturity (75 g). This change represented a net accumulation of 57 g N/vine or 77 kg N/ha. In a separate study, `Seyval blanc' vines were treated with double 15N-labeled ammonium nitrate at either budbreak or bloom. Labeled N was applied as a spray beneath vines to simulate a broadcast vineyard application. Vines were excavated when leaves began to senesce in October, partitioned into various components, and analyzed by mass spectrophotometry to determine fertilizer-derived N content. Vines had recovered statistically similar percentages of fertilizer N applied at budbreak (7.1%) and bloom (10.6%). The low recovery of fertilizer N likely resulted from the method of fertilizer application, the presence of a competitive grass sod between the rows, and relatively high native soil N levels.

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Manuel Palada and Deng Lin Wu

Chili pepper (Capsicumannuum cv. Delicacy) was grown in single- and double-bed rainshelters and irrigated using furrow and drip irrigation to determine effect on yield and efficiency of water and nutrient application in the lowland tropics of southern Taiwan during the hot wet season. The experiment was laid out using a split-plot design with four replications. The main plots were rainshelters (single, double, open field) and the two irrigation methods (furrow and drip) were the subplots. Grafted chili seedlings were transplanted in double rows on raised beds at row spacing of 80 cm and plant spacing of 50 cm. The furrow-irrigated crop was applied with basal N-P2O5-K2O at the rate of 180–180–180 kg·ha-1 and 240–150–180 kg·ha-1 of N-P2O5-K2O as sidedressing. The drip-irrigated crop received half of the total rate applied for the furrow-irrigated crop. Significant differences (P < 0.05) in marketable yield were observed between rainshelter treatments. Highest yield (42.2 t·ha-1) was produced from the single-bed rainshelter, and crops grown under double-bed rainshelters produced the lowest marketable yield. Irrigation method did not significantly influence marketable yield, but crops grown under drip irrigation produced a higher yield than furrow-irrigated crops. Nutrient uptake by plants grown under drip irrigation was also higher (P < 0.05) than for furrow-irrigated crops. Water use efficiency was 60.7% higher in drip-irrigated plots. Results indicate that in high rainfall vegetable production areas, drip irrigation minimizes nutrient loss through leaching and maximizes efficiency of fertilizer use.

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Mark Gaskell and Tim Hartz

product cost could stimulate greater use of CRF in field production for a range of horticultural crops. The continued worldwide expansion of microirrigation offers the potential to improve both irrigation and fertilizer use efficiency. This irrigation

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Hagai Yasuor, Alon Ben-Gal, Uri Yermiyahu, Elie Beit-Yannai and Shabtai Cohen

.M.S. Munoz-Carpena, R. Icerman, J. 2009 Tomato nitrogen accumulation and fertilizer use efficiency on a sandy soil, as affected by nitrogen rate and irrigation scheduling Agr. Water Mgt. 96 1247 1258 Table S1. Plant organ dry matter yield and dry matter

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Ertan Yildirim, Huseyin Karlidag, Metin Turan, Atilla Dursun and Fahrettin Goktepe

efficiency of applied fertilizers, reducing cost of inputs and preventing loss of nutrients to ecosystems ( Baligar et al., 2001 ). Fertilizer use efficiency can be optimized by fertilizer management practices that apply nutrients at the right rate, time, and

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Bernadine Strik, Timothy Righetti and Gil Buller

Fertilizer nitrogen (FN) recovery, and changes in nitrogen (N) and dry weight partitioning were studied over three fruiting seasons in June-bearing strawberry (Fragaria ×ananassa Duch. `Totem') grown in a matted row system. Fertilizer nitrogen treatments were initiated in 1999, the year after planting. The standard ammonium nitrate N application at renovation (55 kg·ha-1 of N) was compared to treatments where additional N was applied. Supplemental treatments included both ground-applied granular ammonium nitrate (28 kg·ha-1 of N) applied early in the season and foliar urea [5% (weight/volume); 16 kg·ha-1 of N] applied early in the season and after renovation. When labeled N was applied (eight of nine treatments) it was applied only once. The impact of no FN from the second through the third fruiting season was also evaluated. Fertilizer nitrogen treatment had no impact on total plant dry weight, total plant N, yield or fruit quality from the first through the third fruiting seasons. Net dry matter accumulation in the first fruiting season was 2 t·ha-1 not including the 4 t·ha-1 of dry matter removed when leaves were mowed during the renovation process. Seasonal plant dry weight and N accumulation decreased as the planting aged. Net nitrogen accumulation was estimated at 40 kg·ha-1 from spring growth to dormancy in the first fruiting season (including 30 kg·ha-1 in harvested fruit, but not including the 52 kg·ha-1 of N lost at renovation). Recovery of fertilizer N ranged from 42% to 63% for the broadcast granular applications and 15% to 52% for the foliar FN applications, depending on rate and timing. Fertilizer N from spring applications (granular or foliar) was predominantly partitioned to leaves and reproductive tissues. A large portion of the spring applied FN was lost when plants were mowed at renovation. Maximum fertilizer use efficiency was 42% for a granular 55 kg·ha-1 application at renovation, but declined to 42% just before plant growth the following spring, likely a result of FN loss in leaves that senesced. In June, ≈30% of the N in strawberry plants was derived from FN that was applied at renovation the previous season, depending on year. This stored FN was reallocated to reproductive tissues (22% to 35%) and leaves (43% to 53%), depending on year. Applying fertilizer after renovation increased the amount of remobilized N to new growth the following spring. The following June, 15% of plant nitrogen was derived from fertilizer applied at renovation 2 years prior.