Maize yields were also significantly higher in Thyolo (2590 kg/ha as average over the three years) than in other districts. Maize yields were particularly skewed in Machinga district (mean yield of 1400 kg/ha against a median yield of only 457 kg/ha). Hybrid maize yields were found to be significantly higher (about 320 kg/ha higher) than the yields of local maize also after controlling for differences in fertilizer and manure use (using propensity score matching). There was a significant positive trend in maize yields from 2006 to 2009 with an increase in mean yields of about 600 kg/ha from 1440 to 2040 kg/ha for hybrid maize and from 1120 to 1680 kg/ha for local maize. These findings illustrate that there is still a lot of room for yield improvement, particularly for hybrid maize. Only in Thyolo district were fertilizer use levels at the recommended levels on average (345 kg/ha) while the median fertilizer use level was 200 kg/ha. In the other districts mean fertilizer levels were 140-210 kg/ha and median levels were 70-125 kg/ha with more than 25% of the maize plots receiving no fertilizer in Chiradzulu, Machinga, Kasungu and Lilongwe districts. The mean fertilizer levels increased from 193 kg/ha in 2006 to 211 kg/ha in 2009 on all maize plots and the distribution became less skewed over time with more than 75% of the plots receiving fertilizers in 2009 and a median fertilizer rate of 151 kg/ha in 2009 against 107 and 64 kg/ha in 2007 and 2006.