Nitrogen fixation in summer-grown soybean crops and fate of fixed-N over a winter fallow in subtropical sugarcane systems

Soil Research ◽  
2019 ◽  
Vol 57 (8) ◽  
pp. 845
Author(s):  
Lee J. Kearney ◽  
Emma Dutilloy ◽  
Terry J. Rose

Legumes including soybeans (Glycine max L.) can provide substantial nitrogen (N) inputs into cropping systems when grown as a part of a rotation. However, in the wet subtropics where land is fallowed for 4–6 months after soybean crops before planting of sugarcane (Saccharum L. spp. hybrids), climatic conditions over winter can be conducive to rapid mineralisation of N from residues with consequent N losses through nitrate leaching or denitrification processes. Using 15N natural abundance methodology, we estimated N2 fixation in 12 summer-grown soybean crops in the Australian wet subtropics, and tracked the fate of soybean residue-N from brown manure crops (residue from plants at late pod-filling left on the soil surface) using 15N-labelled residue in three of these fields over the winter fallow period. Disregarding two poor crops, N2 fixation ranged from 100–290 kg N ha–1 in shoots at mid pod-filling, equating to 170–468 kg N ha–1 including estimated root N contributions. Following the winter fallow, 61 and 68% of soybean residue-N was recovered in clay and peat soils respectively, to 0.9 m depth at one location (Coraki) but only 55% of residue-N could be accounted for to 0.9 m depth in a sandy soil at another location (Ballina). In addition, around 20% of the recovered 15N at this site was located at 0.3–0.6 m depth in the soil profile. Our results indicate that substantial loss of soybean residue-N can occur during winter fallows in the wet subtropics, suggesting that winter cover crops may be necessary to retain N in fields and minimise losses to the environment.

2014 ◽  
Vol 7 ◽  
pp. ASWR.S13861 ◽  
Author(s):  
Corey G. Lacey ◽  
Shalamar D. Armstrong

Little is known about the timing and quantity of nitrogen (N) mineralization from cover crop residue following cover crop termination. Therefore, the objective of this study was to examine the impact of cover crop species on the return of fall applied N to the soil in the spring following chemical and winter terminations. Fall N was applied (200 kg N ha−1) into a living stand of cereal rye, tillage radish, and control (no cover crop). After chemical termination in the spring, soil samples were collected weekly and were analyzed for inorganic N (NO3-N and NH4-N) to investigate mineralization over time. Cereal rye soil inorganic N concentrations were similar to that of the control in both the spring of 2012 and 2013. Fall N application into tillage radish, cereal rye, and control plots resulted in an average 91, 57, and 66% of the fall N application rate as inorganic N in the spring at the 0-20 cm depth, respectively. The inclusion of cover crops into conventional cropping systems stabilized N at the soil surface and has the potential to improve the efficiency of fall applied N.


HortScience ◽  
1999 ◽  
Vol 34 (3) ◽  
pp. 558A-558
Author(s):  
Chad M. Hutchinson ◽  
Milton E. McGiffen

The goals of sustainable agriculture include decreased reliance on synthetic nutrients and pesticides and improved environmental quality for the long-term benefit of the land, livelihood of growers, and their communities. Cropping systems that maximize these goals use alternative fertility and pest control options to produce crops with minimal soil erosion and nutrient leaching. Cropping system elements that can help achieve these goals include: reduced tillage, cover crops, and organic soil amendments. Cover crops are grown before the cash crop and used to replenish the soil with nitrogen and organic matter. Cover crops often also influence pest populations and can be selected based on site-specific growing conditions. Cover crops can be mulched on the soil surface to prevent erosion and weed emergence or can be tilled directly into the soil to incorporate nitrogen and organic matter. Green waste mulch is an increasingly used soil amendment. Many municipalities are encouraging farmers to use green waste mulch in farming systems as an alternative to green waste disposal in landfills. Reduced tillage was once restricted to large-seeded field crops but recent technical advances have made it a feasible option for vegetables and other horticultural crops. Alternative farming practices; however, are still only used by a small minority of growers. Increases in price for organic produce and changes in laws governing farming operations may increase adoption of alternatives to conventional agriculture.


2019 ◽  
Vol 7 (1) ◽  
pp. 103
Author(s):  
Patrick J Trail ◽  
Tim N Motis ◽  
Abram J Bicksler

While maintaining adequate levels of soil fertility can be a challenge on any farm, maintaining those levels on the resource-limited smallholder farms of the tropics requires options that are also affordable, practical, and appropriate in such challenging conditions. This research endeavor was designed to compare the adaptability and potential of four legume species promoted as Green Manure/Cover Crops (GMCC’s) in Southeast Asia. Cowpea (Vigna unguiculata), Jackbean (Canavalia ensiformis), Lablab (Lablab purpureus), and Ricebean (Vigna umbellata) were planted in field trials in five diverse countries across Southeast Asia in 2016, including Cambodia, Myanmar, Thailand, Bangladesh, and the Philippines. Data was collected to assess the production of above-ground biomass, percentage of ground cover, and timing of growth cycles at each site. Although results varied from country to country based on soil-type, climatic conditions, and growing degree days, Jackbean consistently outperformed other GMCC species in terms of biomass production, yielding up to 12 t ha-1 on a dry-weight basis in Bangladesh and the Philippines. Of the four crops compared, cowpea consistently delivered the shortest growth cycle, reaching the pod formation stage in the fewest number of days across all five sites. These results provide informative answers regarding the growth habits and life cycles of these four crops across five diverse sites, and serve to enhance the capability of smallholders in Southeast Asia to select appropriate species needed for soil improvement purposes in a wide-ranging set of cropping systems.


2013 ◽  
Vol 37 (6) ◽  
pp. 1689-1698 ◽  
Author(s):  
Mastrângello Enívar Lanzanova ◽  
Flávio Luiz Foletto Eltz ◽  
Rodrigo da Silveira Nicoloso ◽  
Elemar Antonino Cassol ◽  
Ildegardis Bertol ◽  
...  

Soil erosion is one of the chief causes of agricultural land degradation. Practices of conservation agriculture, such as no-tillage and cover crops, are the key strategies of soil erosion control. In a long-term experiment on a Typic Paleudalf, we evaluated the temporal changes of soil loss and water runoff rates promoted by the transition from conventional to no-tillage systems in the treatments: bare soil (BS); grassland (GL); winter fallow (WF); intercrop maize and velvet bean (M+VB); intercrop maize and jack bean (M+JB); forage radish as winter cover crop (FR); and winter cover crop consortium ryegrass - common vetch (RG+CV). Intensive soil tillage induced higher soil losses and water runoff rates; these effects persisted for up to three years after the adoption of no-tillage. The planting of cover crops resulted in a faster decrease of soil and water loss rates in the first years after conversion from conventional to no-tillage than to winter fallow. The association of no-tillage with cover crops promoted progressive soil stabilization; after three years, soil losses were similar and water runoff was lower than from grassland soil. In the treatments of cropping systems with cover crops, soil losses were reduced by 99.7 and 66.7 %, compared to bare soil and winter fallow, while the water losses were reduced by 96.8 and 71.8 % in relation to the same treatments, respectively.


Author(s):  
Helena Aronsson

Growing a cover crop between main crops imitates natural ecosystems where the soil is continuously covered with vegetation. This is an important management practice in preserving soil nutrient resources and reducing nitrogen (N) losses to waters. Cover crops also provide other functions that are important for the resilience and long-term stability of cropping systems, such as reduced erosion, increased soil fertility, carbon sequestration, increased soil phosphorus (P) availability, and suppression of weeds and pathogens. Much is known about how to use cover crops to reduce N leaching, for climates where there is a water surplus outside the growing season. Non-legume cover crops reduce N leaching by 20%–80% and legumes reduce it by, on average, 23%. There are both synergies and possible conflicts between different environmental and production aspects that should be considered when developing efficient and multifunctional cover crop systems, but contradictions about different functions provided by cover crops can sometimes be overcome with site-specific adaptation of measures. One example is cover crop effects on P losses. Cover crops reduce losses of total P, but extract soil P to available forms and may increase losses of dissolved P. How to use this effect to increase soil P availability on subtropical soils needs further studies. Knowledge and examples of how to maximize the positive effects of cover crops on cropping systems are improving, thereby increasing the sustainability of agriculture. One example is combined weed suppression in order to reduce dependence on herbicides or intensive mechanical treatment.


2017 ◽  
Vol 12 (3) ◽  
Author(s):  
Paolo Ruisi ◽  
Gaetano Amato ◽  
Giuseppe Badagliacca ◽  
Alfonso Salvatore Frenda ◽  
Dario Giambalvo ◽  
...  

This paper reviews the main results from a set of experiments carried out in a semiarid Mediterranean environment during the past 25 years on faba bean (<em>Vicia faba</em> L.), a crop traditionally grown in southern Italy and Sicily under rainfed conditions. These experiments focused on the residual effects of faba bean on subsequent crop(s) and assessment of the nitrogen (N) balance during the crop cycle, paying attention to both the environmental release of N (losses via volatilisation and denitrification) and estimates of N2 fixation as influenced by tillage system, intercropping, and presence/absence of mycorrhizal inoculum. Faba bean relied on N2 fixation more than other grain legumes typically grown in the Mediterranean region (<em>e.g.</em>, chickpea). Contributing reasons were the higher plant N demand of faba bean and its lower capacity to use soil mineral N. This implies higher N benefits for subsequent crop(s) as well as higher risk of N losses from the plant–soil– atmosphere system via leaching, denitrification, and volatilisation. Results from these experiments contribute to better defining the role of faba bean in Mediterranean agro-ecosystems and to identifying technical solutions that maximise the potential benefits of faba bean as a fertility-building crop.


2016 ◽  
Vol 8 (2) ◽  
pp. 159
Author(s):  
Richard Barber

We analyzed the priorities for research and extension that would allow farmers to leave an adequate residue cover on the soil surface, without dirninishing the availability of livestock fodder. We evaluated: 1. The identification of the minimum percentage residue cover to reduce erosion and to promote sustainability for different slope gradients, soil cropping systems and agroecological zones. 2. The practices to improve soil fertility. 3. The selection of improved varieties of grain crops and studies on their association with legume cover crops. 4. Modifications in the residue management 5. The production of alternative livestock feeds for the dry season, to reduce the pressure on residues from livestock. 6. The training of farmers on the need to adopt rational systems of residue utilization, to ensure greater sustainability. We found that to promote sustainability in grain cropping systems, it is essential to carry out carry research and extension activities related to the management of both livestock and grain crops.


Author(s):  
V. P. Belobrov ◽  
S. А. Yudin ◽  
V. А. Kholodov ◽  
N. V. Yaroslavtseva ◽  
N. R. Ermolaev ◽  
...  

The influence of different systems of soil cultivation is considered - traditional (recommended) technology and direct sowing, which is increasingly used under dry conditions of the region. The rehabilitation of the degraded southern chernozems and dark chestnut soils structure during 13 and 7 years of direct sowing, respectively, has not been established. It takes much longer to rehabilitation the aggregate state of soils, which is currently in a critical condition of the content of aggregates> 10 mm in size and the sum of agronomically valuable aggregates. The soils under 60-year treeline, as a control, showed a satisfactory range of aggregates, which indicates a high degree of soil degradation in the past and a long period of their recovery time. The effectiveness of direct sowing usage in the cultivation of a wider range of grain and row crops (winter wheat, sunflower, peas, chickpeas, rapeseed, buckwheat, corn) is due to the peculiarities of agricultural technologies. Abandoning of naked fallows and soil treatments with the simultaneous use of plant residues and cover crops on the soil surface between the harvest and sowing of winter crops provides an anti-erosion effect and, as a consequence, a decrease in physical evaporation, an increase in moisture and biota reserves, an increase in microbiological processes, which are noted in the form trends in improving the agrochemical and agrophysical properties of soils.


Agriculture ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 47
Author(s):  
Kai Yang ◽  
Zejun Tang ◽  
Jianzhang Feng

Sandy soils are prone to nutrient losses, and consequently do not have as much as agricultural productivity as other soils. In this study, coal fly ash (CFA) and anionic polyacrylamide (PAM) granules were used as a sandy soil amendment. The two additives were incorporated to the sandy soil layer (depth of 0.2 m, slope gradient of 10°) at three CFA dosages and two PAM dosages. Urea was applied uniformly onto the low-nitrogen (N) soil surface prior to the simulated rainfall experiment (rainfall intensity of 1.5 mm/min). The results showed that compared with no addition of CFA and PAM, the addition of CFA and/or PAM caused some increases in the cumulative NO3−-N and NH4+-N losses with surface runoff; when the rainfall event ended, 15% CFA alone treatment and 0.01–0.02% PAM alone treatment resulted in small but significant increases in the cumulative runoff-associated NO3−-N concentration (p < 0.05), meanwhile 10% CFA + 0.01% PAM treatment and 15% CFA alone treatment resulted in nonsignificant small increases in the cumulative runoff-associated NH4+-N concentration (p > 0.05). After the rainfall event, both CFA and PAM alone treatments increased the concentrations of NO3−-N and NH4+-N retained in the sandy soil layer compared with the unamended soil. As the CFA and PAM co-application rates increased, the additive effect of CFA and PAM on improving the nutrient retention of sandy soil increased.


2021 ◽  
Vol 41 (4) ◽  
Author(s):  
Carolina Rodriguez ◽  
Linda-Maria Dimitrova Mårtensson ◽  
Erik Steen Jensen ◽  
Georg Carlsson

AbstractDiversifying cropping systems by increasing the number of cash and cover crops in crop rotation plays an important role in improving resource use efficiency and in promoting synergy between ecosystem processes. The objective of this study was to understand how the combination of crop diversification practices influences the performance of arable crop sequences in terms of crop grain yield, crop and weed biomass, and nitrogen acquisition in a temperate climate. Two field experiments were carried out. The first was a 3-year crop sequence with cereal or grain legume as the first crops, with and without undersown forage legumes and forage legume-grass crops, followed by a cereal crop. The second experiment was a 2-year crop sequence with cereal or legume as the first crops, a legume cover crop, and a subsequent cereal crop. For the first time, crop diversification practices were combined to identify plant-plant interactions in spatial and temporal scales. The results partly confirm the positive effect of diversifying cereal-based cropping systems by including grain legumes and cover crops in the crop sequence. Legume cover crops had a positive effect on subsequent cereal grain yield in one of the experiments. Using faba beans as the first crop in the crop sequence had both a positive and no effect on crop biomass and N acquisition of the subsequent cereal. In cover crops composed of a forage legume-grass mixture, the grass biomass and N acquisition were consistently increased after the grain legume, compared to the cereal-preceding crop. However, differences in the proportion of legume to grass in mixture did not influence crop yield or N acquisition in the subsequent cereal. In conclusion, these results support that increased crop diversity across spatial and temporal scales can contribute to resource-efficient production and enhance the delivery of services, contributing to more sustainable cropping systems.


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