Modelling a Millet Cover Crop and Subsequent Maize Production in the Tropical Cerrados of Brazil

Estimation of clover content of mixed swards is difficult in practise. We are currently in the processof developing several on-farm methods for clover content estimation. 1. Photos with various clovercontents are published in the Internet. 2. Yield samples with known area from several points of thefield are separated for clovers and grasses and weighted. 3. The clover content of yield (% in drymatter) can be calculated with formula: y=23.90Ln(number of clover plants m in spring) 18.759. IntroductionLegume-based mixed swards are the most important source of nitrogen in organic farming and ofhigh value in animal nutrition. In Finland, red clover (Trifolium pratense) is the most commonfodder legume in mixed swards. It is important to know legume content of the mixed sward tooptimise harvesting time of silage and feeding of cattle. Legume content gives also an estimation ofthe amount of biological nitrogen fixation. However, estimation of clover content is difficult or timeand work consuming in practise on a field. Material and methodsAn existing field experiment with plots of various clover contents was used to test and developthree different methods for clover content estimation on-farm in 2003. The experiment wasestablished in 2001 with seed mixture of red clover (Trifolium pratense), timothy (Phleum ptatense)and tall fescue (Festuca arundinacea). Sub-plots of size 0.5m x 0.5m were used for themeasurements of the method development. Methods under development are: 1. Photos in theInternet, 2. Yield samples of known area and 3.Clover plants of known area Results1. Photos in the Internet. Photos with various clover contents have been taken and published in theInternet (Figure 1). Photos are from the first and second cut just before harvest. In Finland it isnormal to have two cuts from the legume-based sward for silage. Gustavsson (2001) has also donethis in Sweden, but this is a service for Finnish farmers.