Impact of legume 'break' crops on the yield and grain quality of wheat and relationship with soil mineral N and crop N content

Abstract

The effect of annual 'break' crops on the yield and protein content of wheat was investigated over 3 seasons on a Red Kandasol on the south-western slopes of New South Wales. The 'break' crops included lupin and pea grown for grain, pea and vetch managed for silage, clovers managed for silage or hay, and vetch and clovers managed for green manuring. Wheat was sown for 2 years following the legume year, or canola and wheat followed the legumes. Averaged over 3 experiments the yields of first crop wheat following pea or vetch silage crops were comparable with those after grain pea. Yields following clover forage conservation crops or green manures exceeded those after grain pea by at least 0.41 t/ha; average yield increase after clover green manure was 0.93 t/ha. In one experiment, yields of second crop wheat were greater, by up to 0.37 t/ha, after forage conservation or green manure legume 'breaks' than after grain legumes. In 2 experiments, second crop wheat yields were greater after a first crop of canola than a first crop of wheat. Compared with continuous wheat yield, aggregate mean wheat yield increases were 3.5–4 t/ha following grain legumes, pea, and vetch silage crops, but 5.3–6.3 t/ha following clover forage conservation and green manure crops. However, the relative effects of legume treatments on wheat yield were significantly seasonally dependent. Yield and grain protein variation in wheat after legumes was significantly correlated with variation in mineral N at wheat establishment. However, in one experiment, yield was correlated only with variation in mineral N below the 20-cm soil depth, whereas protein was correlated only with variation in mineral N above the 20 cm soil depth. Yield increases in first crop wheat did not occur at the expense of grain protein.

Magnitude and farm-economic value of grain legume pre-crop benefits in Europe: A review

“…Similarly across different estimates, economic N savings for maximum yields average 23-31 kg ha −1 , and enable average cost savings of 18-24 D ha −1 (2012 urea price averaged over several countries, Eurostat, 2014). This figure for Europe is comparable to the estimates of 12-55 kg ha −1 reported from America or Australia Coxworth, 1987 in Badaruddin andMeyer, 1994;Evans et al, 2003). However, the range of N savings includes low values, i.e.…”

Crop rotation effects on yield of oilseed rape, wheat and barley and residual effects on the subsequent wheat

“…The amount of wheat yield decrease negatively correlated with the simple water balance (rainfall minus evapotranspiration) in May-July. In 2001/2002 and 2002/2003, the preceding crop superimposed the crop rotation effects, thus resulting in similar effects as observed in 1988-2001. Our results clearly reveal the importance of a favourable preceding crop for the yield performance of a crop, especially wheat and OSR.…”

“…OSR or peas provide more N than cereals, which may cause lodging if N fertilization is not modified (Christen 1998). Evans et al (2003) pointed out that not only the total amount, but also the distribution of residual N within the soil profile might influence both the yield and protein content of subsequent wheat crops.…”

Legumes can reduce economic optimum nitrogen rates and increase yields in a wheat–canola cropping sequence in western Canada

“…With the exception of Brandon, there were generally greater non-N benefits for all other preceding crops compared with wheat. The non-N benefits provided by the legumes may have included enhanced water availability (Miller et al, 2003a,b), reduced disease incidence (Stevenson and van Kessel, 1996;Evans et al, 2003) and better root penetration due to improved soil tilth (Grant and Lafond, 1993). Based on the residuals of the regression (Fig.…”