Nitrogen mineralization, nitrate leaching and crop growth after ploughing-in leguminous and non-leguminous grain crop residues

Abstract

A field experiment was conducted in Canterbury, New Zealand to investigate the effect of six leguminous and non-leguminous grain crops on soil N fertility over a 12 month period (March 1989 to March 1990. All crops had an overall negative N balance during their growing season. A greater amount of soil N was removed by barley, rape and lupins (104-119 kg N/ha) than by field beans, field peas or lentils (50-74 kg N/ha).Net N mineralization was measured in all treatments between residue incorporation and the start of winter. With the exception of the lupins, accumulation of mineral N in the soil profile before the start of winter drainage was greater following leguminous (mean 124 kg N/ha) than non-leguminous crops (mean 80 kg N/ha).Cumulative apparent leaching losses over the autumn/winter were largely a reflection of the mineral N content of the profile before the start of drainage. Excluding lupins, leaching losses declined in the order fallow > legumes > non-legumes (110 > 72 > 37 kg N/ha respectively). The anomalous results for the lupins were attributed to the incorporation of a large amount of woody residues after harvest which may well have resulted in extensive net N mineralization occurring later in the autumn.Over a 12 month period, all treatments showed a decline in N fertility (110-160 kg N/ha), although compared with barley, the total loss of soil N was 10-40 kg N/ha less following leguminous crops.Growth of the following spring wheat test crop was affected by the preceding crop. Grain yield, grain N yield and total N yield were significantly related to the mineral N content of the soil at the end of leaching, and to a measure of net N mineralization during the growing season of the test crop.

The effect of incorporation time of different crops on the residual effect on spring cereals

“…Soil conditions suitable for N mineralization after late autumn incorporation was concluded to last generally too short time under Finnish conditions to result in substantial net N mineralization before spring. Thus the release of N from incorporated plant biomass during the following summer can be essential for the yield of the following crop, accordingly to Francis et al (1994), who found that grain yield of spring wheat correlated positively with net N mineralization during the growing season after crops with a different N content. Francis et al (1994) also found that grain yield of spring wheat correlated positively with soil mineral N content before the growing season.…”

“…Thus the release of N from incorporated plant biomass during the following summer can be essential for the yield of the following crop, accordingly to Francis et al (1994), who found that grain yield of spring wheat correlated positively with net N mineralization during the growing season after crops with a different N content. Francis et al (1994) also found that grain yield of spring wheat correlated positively with soil mineral N content before the growing season. In the present study however, the yield could not be deduced from the soil N contents, as in general spring barley yields were similar after early and late autumn ploughing.…”

Effect of temperature and precipitation on nitrate leaching from organic cereal cropping systems in Denmark

“…The type of the preceding crop affects the amount of residual N during autumn available for leaching. Francis et al (1994) reported from an experiment using rotations with legume and non-legume crops and spring crops that the amount of mineral N remaining in the soil profile in the autumn after harvest of barley and rapeseed crops was about 52 kg N ha −1 . However, after leguminous crops, the residual N was generally larger (mean of 80 kg N ha −1 ).…”

Nitrogen contribution of field pea in annual cropping systems. 2. Total nitrogen benefit

“…Generally, plant residues with an N content of less than 1.2-1.3% (C:N ratio of about 30) will immobilize soil N (and fertilizer N, if present); however, if the percent N is more than 1.8-2.0 (C:N ratio of about 20), considerable mineralization usually occurs (Jenkinson 1981;Janzen and Kucey 1988). Indirect calculations of net N mineralization (wheat total N yield minus preseeding soil nitrate-N levels), suggested greater mineralization after a legume than non-legume crop (Francis et al 1994). In a laboratory study, Jensen (1996) found greater mineralization of N in soils collected from field pea than barley (Hordeum vulgare L.) stubble.…”