Cabbage Integrated Pest Management : An Ecological Guide.

Major Agronomic PracticesIn the table below a list of the advantages and disadvantages of both fertilizers is given:Table 3.5.5 : Comparing organic and chemical fertilizersAdvantageDisadvantageOrganic fertilizer• rich in nutrients• usually provide (part of) the micronutrientsN, P & K, and wide range of micronutrients• improves soil structure• increases water holding capacity soil• gradual release of nutrients• improves nutrient exchange system• stimulates activity of micro-organisms thatmake nutrients from the soil available toplants• organic fertilizers such as compost verywidely in composition depending on theraw material used in their preparationChemical fertilizer• high content of a fewnutrients per volume unit (kg)• fast release of nutrients• easy to determine dosage• easy to apply, not labourintensive• usually very water soluble,may be washedaway/drained off quicklyduring wet season• expensive3.5.6 Foliar fertilizersIn some areas, farmers make use of foliar fertilizers. These are solutions of fertilizers that are sprayed onthe leaves of the plant. The advantage of using foliar fertilizer is that it is quickly taken up by the plant,quicker than the nutrient uptake from organic or inorganic fertilizers by the roots. They can be used as acorrective measure for example when a deficiency of a certain nutritional element is discovered. Adisadvantage is that foliar fertilizers are expensive and act very short term - no gradual release of nutrients,no effect on soil structure. And, when not used correctly, foliar fertilizers may cause burning of theleaves. Also, some pest and diseases can become more serious when crops are too generously fertilized.Field studies with foliar fertilizers in Dalat and Hanoi (Vietnam) showed a slight increase in yield but theeconomic efficiency was not clear (FAO- Updates on Vietnam national IPM programme in vegetables, 1999).To see if foliar fertilizers would be economical for use in your field, compare a small area with foliarfertilizers with an area in which common fertilization is used. Note down cost of fertilizers, incidence ofinsect pests and diseases and economic returns.3.5.7 Fertilization needs of cabbageAn indication for the amount of organic and inorganic fertilizers for cabbage are given in the table below.These guidelines are very general and the range in doses for the fertilizers is broad. The exact dosage tobe applied depend on the nutrients already available in the soil (soil test service, see 3.5.2), soil type andstructure, environment, etc. It is recommended to prefer organic above inorganic (chemical) fertilizers!When lots of organic matter is used regularly, the doses of chemical fertilizers can usually be (very) low,a lot lower than indicated in the table!It is recommended to set up a field study to test different types and doses of fertilizers to check the bestcombination for your crop and field situation. In Dalat and Hanoi, Vietnam, for example, cabbage fieldstudies showed that chemical fertilizers alone were not sufficient for good plant development. It was alsoadvised to include proper economic analysis in field experiments as some of the organic fertilizer wasexpensive when bought from elsewhere. (FAO - Updates on Vietnam Nat. IPM programme in vegetables, 1999).Cabbage Ecological Guide - 200034