. 2000. Comparison of nitrogen application via a trickle irrigation system with surface banding of granular fertilizer on red raspberry. Can. J. Plant Sci. 80: 363-371. A field trial compared applications of ammonium nitrate N as soil-surface bands of granular fertilizer with applications as a solution through a trickle irrigation system (i.e., fertigation) on yield, plant growth and end-of-season extractable soil inorganic nitrogen of red raspberries (Rubus idaeous L.). The granular application was made once in early spring, and the fertigation was scheduled as eight weekly applications from early to late spring in each of 4 successive years. Three rates of N (33, 67 and 134 kg N ha -1 ) were applied by both methods and a zero N control was also included. The N treatments had relatively small effects on berry yields, being significant in the last 2 years (1988 and 1989) only. Applications of granular N resulted in equal or greater yields than the control, whereas the fertigation method resulted in equal or lower yields than the control. Granular applications tended to enhance cane growth and N concentrations in the fruiting cluster, laterals and leaves of fruiting canes. Leaching of N during the growing season was greater with the fertigation than with the granular method of application. The poorer performance of fertigation relative to granular application of N was due to the timing of application in relation to crop requirement. Raspberries require a majority of their N early in the growing season. The utility of applying fertilizer N via irrigation systems on crops such as raspberry in climatic regions where water deficits do not usually occur early in the growing season, as in coastal British Columbia, is limited. L'épandage en granulés était fait en une seule fois au début du printemps et la fertirrigation était répartie en 8 distributions hebdomadaires échelonnées du début à la fin du printemps dans chacune de quatre années successives. Trois doses de N: 33, 67 et 134 kg N ha -1 étaient utilisées dans chaque méthode, avec un traitement témoin sans N. La fumure N n'avait que relativement peu d'effet sur le rendement fruitier, les effets n'atteignant le niveau de significativité statistique que dans les deux dernières années, 1988 et 1989. L'épandage en granulés donnait lieu à des rendements égaux ou supérieurs à ceux obtenus sans fumure N, alors qu'en fertirrigation les rendements obtenus ne dépassaient pas ceux du traitement témoin. L'épandage sous forme de granulés paraissait stimuler la croissance des tiges fructifères et la concentration de N dans les grappes de fruits, dans les ramifications latérales et dans les feuilles. Le lessivage de N durant la saison de végétation était plus important en régime de fertirrigation qu'avec l'épandage en granulés. Les moins bonnes performances de la fertirrigation s'expliquent par le manque de concordance chronologique entre les apports de N et les besoins de la culture. Le gros des besoins en N du framboisier survient, en effet, ou début de la saison, si bien qu'...

Oxisols are the dominant soils of the continental shields in the tropics under permanently moist and alternately wet and dry climates. Oxisols have a low cation exchange capacity, high permeability, but low available waterholding capacity. Some have a low pH, which can cause Al3* toxicity to many crops. Together with erratic rainfall patterns, special management methods of soil‐water and plant nutrients for Oxisols are yet to be carefully studied. The relatively recent development of combined high frequency irrigation and fertilizer techniques, “drip fertilization,” may be one of the solutions for intensive production of food crops on Oxisols. A drip irrigation system using porous plastic tubing was designed for a field experiment to study the feasibility and operational techniques of drip irrigation and fertilization management in a highly weathered, acid Oxisol (Coto clay). Green pepper (Capsicum annuum L.), ‘Blanco del Pais’ was the test crop. A randomized, completeblock design was chosen to compare different fertilization techniques. In addition to the check plot, the three other treatments were: fertigation (drip irrigation and drip application of N and K, banded P); drip irrigation with banded N, P, and K; and drip irrigation with broadcast N, P, and K. All treatments, except the control plot, received a total amount of fertilizer equal to 56.8 g of 10‐10‐10 commercially available fertilizer per plant and all treatments were uniformly drip irrigated according to pan evaporation data. Different moisture profiles during the wet (June‐November) and dry (December‐May) seasons were observed. Nutrient movement profiles suggested that the distribution of fertilizer under drip irrigation depended on the method of fertilizer placement. Root development patterns indicated that more than half of the root system (dry weight) was developed in the 5 to 15 cm layer. More fibrous roots were developed toward the porous drip tubing which supplied moisture and nutrients. Yield were significantly different among all treatments during the dry season and the fertigation, broadcast, and control during the wet season. Yields from broadcast fertilizer treatments were 15.8% lower than from fertigation, and 12.3% lower than from banded fertilizer. The results of this research indicates drip fertigation can be a promising alternative to currently used water‐nutrient management methods for Oxisols in the wet‐dry tropics.

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