mead.cowpeamaize: Maize/Cowpea intercropping experiment In agridat: Agricultural Datasets

Description

Maize/Cowpea Intercropping experiment with multiple nitrogen treatments.

Format

A data frame with 72 observations on the following 6 variables.

`block`

block, 3 levels

`nitro`

nitrogen, 4 levels

`cowpea`

cowpea variety, 2 levels

`maize`

maize variety, 3 levels

`cyield`

cowpea yield, kg/ha

`myield`

maize yield, kg/ha

Details

An intercropping experiment conducted in Nigeria. The four nitrogen treatments were 0, 40, 80, 120 kg/ha.

Source

Roger Mead. 1990. A Review of Methodology For The Analysis of Intercropping Experiments. Training Working Document No. 6. CIMMYT. http://repository.cimmyt.org/xmlui/handle/10883/868

References

Roger Mead, Robert N Curnow, Anne M Hasted. 2002. Statistical Methods in Agriculture and Experimental Biology, 3rd ed. Chapman and Hall. Page 390.

Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48``` ```data(mead.cowpeamaize) dat <- mead.cowpeamaize # Cowpea and maize yields are clearly in competition if(require("latticeExtra")){ useOuterStrips(xyplot(myield ~ cyield|maize*cowpea, dat, group=nitro, main="mead.cowpeamaize - intercropping", xlab="cowpea yield", ylab="maize yield", auto.key=list(columns=4))) } # Mead Table 2 Cowpea yield anova...strongly affected by maize variety. anova(aov(cyield ~ block + maize + cowpea + nitro + maize:cowpea + maize:nitro + cowpea:nitro + maize:cowpea:nitro, dat)) # Cowpea mean yields for nitro*cowpea aggregate(cyield ~ nitro+cowpea, dat, FUN=mean) # Cowpea mean yields for each maize variety aggregate(cyield ~ maize, dat, FUN=mean) # Bivariate analysis aov.c <- anova(aov(cyield/1000 ~ block + maize + cowpea + nitro + maize:cowpea + maize:nitro + cowpea:nitro + maize:cowpea:nitro, dat)) aov.m <- anova(aov(myield/1000 ~ block + maize + cowpea + nitro + maize:cowpea + maize:nitro + cowpea:nitro + maize:cowpea:nitro, dat)) aov.cm <- anova(aov(cyield/1000 + myield/1000 ~ block + maize + cowpea + nitro + maize:cowpea + maize:nitro + cowpea:nitro + maize:cowpea:nitro, dat)) biv <- cbind(aov.m[,1:2], aov.c[,2], aov.cm[,2]) names(biv) <- c('df','maize ss','cowpea ss','ss for sum') biv\$'sum of prod' <- (biv[,4] - biv[,2] - biv[,3] ) /2 biv\$cor <- biv[,5]/(sqrt(biv[,2] * biv[,3])) signif(biv,2) ## df maize ss cowpea ss ss for sum sum of prod cor ## block 2 0.290 0.0730 0.250 -0.058 -0.400 ## maize 2 18.000 0.4100 13.000 -2.600 -0.980 ## cowpea 1 0.027 0.0060 0.058 0.013 1.000 ## nitro 3 29.000 0.1100 25.000 -1.800 -0.980 ## maize:cowpea 2 1.100 0.0099 0.920 -0.099 -0.950 ## maize:nitro 6 1.300 0.0680 0.920 -0.200 -0.680 ## cowpea:nitro 3 0.240 0.1700 0.150 -0.130 -0.640 ## maize:cowpea:nitro 6 1.300 0.1400 1.300 -0.033 -0.079 ## Residuals 46 16.000 0.6000 14.000 -1.400 -0.460 ```

agridat documentation built on May 2, 2019, 4:01 p.m.