The Kenaf Plantgreenspun.com : LUSENET : Heifer Project Agro-Ecology : One Thread
Does the kenaf plant deplete the soil of nitrogen more than say, the cotton plant?
-- Anonymous, July 24, 2000
I would guess that the usage of nitrogen is about the same, perhaps a little more for Kenaf. Hoever, Kenaf probably returns more to the soil in good production systems. Other factors include soil loss and pesticide load and this may favour Kenaf.
Other fibre crops to consider include Hemp - whose ecological contribution is excellent.
Some evidence and websites below...
"A kenaf crop of 50 MT green plants/ha withdraws from the soil about 175 kg N, 15 kg P, 75 kg K, 105 kg Ca, and 30 kg Mn (Whitely 1981)."
"Uptake studies across the cotton belt suggest that cotton needs 60 pounds of nitrogen per acre to produce one bale of lint. Why are the recommended rates so much lower? Numerous nitrogen-rate studies in North Carolina and Georgia show that unfertilized soils can supply 40 to 70 pounds of available nitrogen from organic matter, subsoil storage, and rainfall. Soil nitrogen reserves are generally higher on the more productive loamy soils. A good crop of soybeans or peanuts will supply an additional 20 to 30 pounds of nitrogen per acre. When soil nitrogen reserves are included, the recommended rates are consistent with a range of total available nitrogen from 110 to 170 pounds per acre following peanuts or soybeans, or from 90 to 140 pounds per acre following other crops. In general, soils with more than 16 inches of soil covering the subsoil hold less reserve nitrogen and require the highest rates of nitrogen. Loams and finer- textured soils have higher nitrogen reserves and require the lowest rates of nitrogen. Higher yields in irrigated fields can justify an additional 15 to 25 pounds of nitrogen per acre (see the "Nitrogen, Pix, and Irrigation" section of this chapter)."
Kenaf also uses a lot of Potassium
"Soil Analysis Initial soil analysis of the research plots prior to the first fertilizer application and planting in 1989 had an analysis of 9.0 N, 64 P, and 170 K kg/ha. In the final year of the research, 1991, the soil K content at planting and harvest was significantly different among cropping sequences, while the pH and N were only significantly different for samples collected at harvest (Table 6). When comparing K values between planting and harvest, the cropping sequences with kenaf had the greatest drop in soil K values planting to harvest. Not only did the kenaf crops deplete a greater amount of K during the growing season, but the slight net gain in K for two of the three soybean sequences indicates that the addition of 42 kg/ha of K at planting served as an adequate soil maintenance application for the soybean crops."
HEMP pages "Hemp Agronomic Characteristics Hemp is a bast fiber plant similar to flax, kenaf, jute and ramie. Long slender primary fibers on the outer portion of the stalk characterize bast fiber plants. An annual plant that grows from seed, hemp can be grown on a range of soils, but tends to grow best on land that produces high yields of corn. The soil must be well drained, rich in nitrogen, and non-acidic. Hemp requires limited pesticides because is grows so quickly and attracts few pests. In northern latitudes, hemp is usually planted between early March and late May. Hemp averages between 2 - 4 meters in height in about four months of growth"
"Cultivation of Hemp
Since Germanys rediscovery of hemp in 1993, the terms hemp and ecology have become more closely associated in the German language. Hemp is now regarded as the environmentally friendly natural resource. According to one report, Hemp is well suited for sustainable, ecologically sound agriculture, which is in increasing demand in Europe. Hemp - almost automatically - provides clean bioresources that are ready for the development of environmentally friendly products. (Hingst/Mackwitz 1996)"
You are on the agroeco-l listerver?
Quite a lot being added
-- Anonymous, July 31, 2000
Am I on the list server?
-- Anonymous, August 09, 2000