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Leaching and plant offtake of N in field pea/cereal cropping sequences with incorporation of 15 N‐labelled pea harvest residues
Author(s) -
Thomsen I.K.,
Kjellerup V.,
Christensen B.T.
Publication year - 2001
Publication title -
soil use and management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.709
H-Index - 81
eISSN - 1475-2743
pISSN - 0266-0032
DOI - 10.1111/j.1475-2743.2001.tb00029.x
Subject(s) - lysimeter , hordeum vulgare , sativum , agronomy , field pea , leaching (pedology) , loam , straw , nitrate , pisum , white mustard , crop , biology , crop residue , cropping system , poaceae , horticulture , chemistry , soil water , ecology , agriculture
. Field peas ( Pisum sativum L.) were grown in sequence with winter wheat ( Triticum aestivum L.) or spring barley ( Hordeum vulgare L.) in large outdoor lysimeters. The pea crop was harvested either in a green immature state or at physiological maturity and residues returned to the lysimeters after pea harvest. After harvest of the pea crop in 1993, pea crop residues (pods and straw) were replaced with corresponding amounts of 15 N‐labelled pea residues grown in an adjacent field plot. Reference lysimeters grew sequences of cereals (spring barley/spring barley and spring barley/winter wheat) with the straw removed. Leaching and crop offtake of 15 N and total N were measured for the following two years. These treatments were tested on two soils: a coarse sand and a sandy loam. Nitrate concentrations were greatest in percolate from lysimeters with immature peas. Peas harvested at maturity also raised the nitrate concentrations above those recorded for continuous cereal growing. The cumulative nitrate loss was 9–12 g NO 3 ‐N m –2 after immature peas and 5–7 g NO 3 ‐N m –2 after mature peas. Autumn sown winter wheat did not significantly reduce leaching losses after field peas compared with spring sown barley. 15 N derived from above‐ground pea residues accounted for 18–25% of the total nitrate leaching losses after immature peas and 12–17% after mature peas. When compared with leaching losses from the cereals, the extra leaching loss of N from roots and rhizodeposits of mature peas were estimated to be similar to losses of 15 N from the above‐ground pea residues. Only winter wheat yield on the coarse sand was increased by a previous crop of peas compared to wheat following barley. Differences between barley grown after peas and after barley were not statistically significant. 15 N lost by leaching in the first winter after incorporation accounted for 11–19% of 15 N applied in immature pea residues and 10–15% of 15 N in mature residues. Another 2–5% were lost in the second winter. The 15 N recovery in the two crops succeeding the peas was 3–6% in the first crop and 1–3% in the second crop. The winter wheat did not significantly improve the utilization of 15 N from the pea residues compared with spring barley.