Nitrogen use efficiency of monoculture and hedgerow intercropping in the humid tropics

Abstract

The design of productive and efficient intercropping systems depends on achieving complementarity between component species' resource capture niches. Spatiotemporal patterns of capture and use of pruning and urea nitrogen (N) by trees and intercrops were elucidated by isotopic tracing, and consequences for nitrogen use efficiency were examined. During the first cropping season after applying urea-15 N, maize accounted for most of the plant 15 N recovery in Peltophorum dasyrrachis (33.5%) and Gliricidia sepium (22.3%) hedgerow intercropping systems. Maize yield was greatest in monoculture, and maize in monoculture also recovered a greater proportion of urea 15 N (42%) than intercropped maize. Nitrogen recovery during active crop growth will not be increased by hedgerow intercropping if hedgerows adversely affect crop growth through competition for other resources. However, hedgerows recovered substantial amounts of 15 N during both cropping cycles (e.g. a total of 13-22%), showing evidence of spatio-temporal complementarity with crops in the spatial distribution of roots and the temporal distribution of N uptake. The degree of complementarity was species-specific, showing the importance of selecting appropriate trees for simultaneous agroforestry. After the first cropping season 17-34% of 15 N applied was unaccounted for in the plant-soil system. Urea and prunings N were recovered by hedgerows in similar amounts. By the end of the second (groundnut) cropping cycle, total plant 15 N recovery was similar in all cropping systems. Less N was taken up by the maize crop from applications of labelled prunings (5-7%) than from labelled urea (22-34%), but the second crop recovered similar amounts from these two sources, implying that prunings N is more persistent than urea N. More 15 N was recovered by the downslope hedgerow than the upslope hedgerow, demonstrating the interception of laterally flowing N by hedgerows.

Complementary resource use by tree species in a rain forest tree plantation

“…Similar separation of nutrient demand or seasonal complementarity has been observed in experimental grassland biodiversity plots, leading to higher total resource use (Hooper and Vitousek 1998) and greater input and retention of N in biodiverse systems (Fargione et al 2007). Temporal complementarity has also been observed in agroforestry systems, where seasonal and spatial separation of soil N uptake between crops and trees has led to higher productivity (Schroth 1999, Rowe et al 2005.…”

Desempenho agronômico de feijão‑caupi e milho semeados em faixas na safrinha

“…Essas faixas podem ser suficientemente largas para permitir a mecanização, sem que se perca a vantagem da associação. Além de permitir o manejo independente de cada cultura, o que favorece a mecanização dos tratos culturais, esse sistema de cultivo também contribui para o melhor aproveitamento de luz solar (Tsubo et al, 2002;Awal et al, 2006), água (Souza et al, 2011) e nutrientes (Rowe et al, 2005;Dahmardeh et al, 2010) pelas culturas, com uso mais eficiente da área. O cultivo em faixas também contribui para a redução da erosão; possibilita a diversificação da produção, no espaço e no tempo; favorece o controle de plantas daninhas; e contribui para a fertilidade do solo, pela ciclagem de nutrientes e pela fixação de N 2 , quando associado com leguminosas (Sermenh et al, 2007).…”

Plant-soil biodiversity relationships and nutrient retention in agricultural riparian zones of the Sacramento Valley, California

“…Vegetated riparian buffers filter agricultural nutrients and pollutants, reduce erosion, improve water quality and provide reservoirs for biodiversity (Lovell and Sullivan 2006;Peterjohn and Correll 1984;Richardson et al 2007). Multi-species riparian buffers that include herbaceous as well as woody species may result in higher total productivity, soil carbon (C) sequestration, and nitrogen (N) immobilization than monoculture plantings (Hill 1996;Marquez et al 1999;Rowe et al 2005;Tufekcioglu et al 1998).…”