Tropical Soils and Food Security: The Next 50 Years

Stocking, Michael

doi:10.1126/science.1088579

Cited by 216 publications

(128 citation statements)

References 23 publications

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“…Food security will become increasingly challenged over the upcoming decades by climate change [1,2], natural resource degradation [3], and a burgeoning global population [4]. Smallholder farming systems are of particular concern given that farmers often do not have access to the inputs and technologies necessary for high-production agriculture [5], and many of these systems are distributed across the tropics, where negative climate change impacts are expected to be greatest [2,6].…”

Section: Background and Rationalementioning

confidence: 99%

Mapping Smallholder Wheat Yields and Sowing Dates Using Micro-Satellite Data

et al. 2016

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Abstract:Remote sensing offers a low-cost method for developing spatially continuous crop production statistics across large areas and through time. Nevertheless, it has been difficult to characterize the production of individual smallholder farms, given that the land-holding size in most areas of South Asia (<2 ha) is smaller than the spatial resolution of most freely available satellite imagery, like Landsat and MODIS. In addition, existing methods to map yield require field-level data to develop and parameterize predictive algorithms that translate satellite vegetation indices to yield, yet these data are costly or difficult to obtain in many smallholder systems. To overcome these challenges, this study explores two issues. First, we employ new high spatial (2 m) and temporal (bi-weekly) resolution micro-satellite SkySat data to map sowing dates and yields of smallholder wheat fields in Bihar, India in the 2014-2015 and 2015-2016 growing seasons. Second, we compare how well we predict sowing date and yield when using ground data, like crop cuts and self-reports, versus using crop models, which require no on-the-ground data, to develop and parameterize prediction models. Overall, sow dates were predicted well (R 2 = 0.41 in 2014-2015 and R 2 = 0.62 in 2015-2016), particularly when using models that were parameterized using self-report sow dates collected close to the time of planting and when using imagery that spanned the entire growing season. We were also able to map yields fairly well (R 2 = 0.27 in 2014-2015 and R 2 = 0.33 in 2015-2016), with crop cut parameterized models resulting in the highest accuracies. While less accurate, we were able to capture the large range in sow dates and yields across farms when using models parameterized with crop model data and these estimates were able to detect known relationships between management factors (e.g., sow date, fertilizer, and irrigation) and yield. While these results are specific to our study site in India, it is likely that the methods employed and the lessons learned are applicable to smallholder systems more generally across the globe. This is of particular interest given that similar high spatio-temporal resolution micro-satellite data will become increasingly available in the coming years.

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Section: Background and Rationalementioning

confidence: 99%

Mapping Smallholder Wheat Yields and Sowing Dates Using Micro-Satellite Data

et al. 2016

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“…mollisols in the great plains of the USA) maintain very high levels of productivity for long periods of time, despite these losses. Other soils, especially after years of annual cropping in tropical climates, suffer from degradation processes such as losses in soil carbon, nutrient depletion and reduced waterholding capacity, which can occur quickly and be difficult to reverse (Stocking, 2003). Making provision for both improved soil management in agricultural systems and avoided deforestation in the CDM-AR could extend the provision of ecosystem service payments directly towards addressing the enormous issue of ongoing and increasing land degradation in developing and tropical countries.…”

Section: Resultsmentioning

confidence: 99%

Carbon sequestration, land degradation and water.

Trabucco¹,

Bossio²,

Straaten³

et al. 2008

Conserving Land, Protecting Water

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This paper focuses on two environmental issues on which the Kyoto Protocol treaty, and CDM-AR projects in particular, may have direct environmental impacts: ongoing human-induced land degradation, and the water-use implications of carbon sequestration projects. An overview is given of afforestation/reforestation and terrestrial carbon fixation as a climate change mitigation measure, and its importance and potential contribution is evaluated within the Kyoto Protocol framework. The extent, location, productivity, current land use and population of land suitable for CDM-AR are analysed, and the area of this land that will be required to satisfy carbon emission offset limits are evaluated. The potential scope for CDM-AR to address land degradation, and, with a simple water balance model, its potential water-use impacts, are discussed. Results are derived from a global geospatial analysis that estimates the impacts on land and water resources.

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“…Even where the above-ground biomass of velvet bean has been removed, there may be significant amounts of N added to the soil in the form of dead roots, nodules and other contributions from rhizodeposition. Recovery of roots of grain legumes has indicated that about 10% or less of the plant N is present in roots at harvest (Stocking, 2003). Considerably more N may be present in the root systems of growing plants (Giller, 2001).…”

Section: Discussionmentioning

confidence: 99%

Partial Nutrient Balances in Tropical Velvet Bean-Maize System in Zimbabwe

Jiri¹,

Mafongoya²

2017

JAS

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In a field experiment on legume-maize cropping sequence, the effect of nitrogen and phosphate fertiliser application on nutrient budgeting after a two year cropping cycle was studied. The results of this work showed that partial nutrient balances can give an indication about the sustainability of a system unless a full stock of all the nutrients is known. It is also clear from these results that there would unlikely be a carryover of N to the next season, probably due to leaching of N from the top soil. Positive partial P balances would, on the other hand, be of residual value. However, it should be noted that the positive partial P balances were only observed where maize yield was low. The long-term perspectives of a crop production system cannot be assessed solely on the basis of partial nutrient balances. The nutrient stock: balance ratio may be a better indicator of sustainability, giving a more accurate indication of how long farming can continue in the same way, given the available nutrients. These points towards taking a fresh look at the existing recommended application rates for maize crops.

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Tropical Soils and Food Security: The Next 50 Years

Cited by 216 publications

References 23 publications

Mapping Smallholder Wheat Yields and Sowing Dates Using Micro-Satellite Data

Mapping Smallholder Wheat Yields and Sowing Dates Using Micro-Satellite Data

Carbon sequestration, land degradation and water.

Partial Nutrient Balances in Tropical Velvet Bean-Maize System in Zimbabwe

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