Expansion Of Crop Production Research Articles

Inspecting the Food–Water Nexus in the Ogallala Aquifer Region Using Satellite Remote Sensing Time Series

Agricultural production in the Great Plains provides a significant amount of food for the United States while contributing greatly to farm income in the region. However, recurrent droughts and expansion of crop production are increasing irrigation demand, leading to extensive pumping and attendant depletion of the Ogallala aquifer. In order to optimize water use, increase the sustainability of agricultural production, and identify best management practices, identification of food–water conflict hotspots in the Ogallala Aquifer Region (OAR) is necessary. We used satellite remote sensing time series of agricultural production (net primary production, NPP) and total water storage (TWS) to identify hotspots of food–water conflicts within the OAR and possible reasons behind these conflicts. Mean annual NPP (2001–2018) maps clearly showed intrusion of high NPP, aided by irrigation, into regions of historically low NPP (due to precipitation and temperature). Intrusion is particularly acute in the northern portion of OAR, where mean annual TWS (2002–2020) is high. The Oklahoma panhandle and Texas showed large decreasing TWS trends, which indicate the negative effects of current water demand for crop production on TWS. Nebraska demonstrated an increasing TWS trend even with a significant increase of NPP. A regional analysis of NPP and TWS can convey important information on current and potential conflicts in the food–water nexus and facilitate sustainable solutions. Methods developed in this study are relevant to other water-constrained agricultural production regions.

Land Use Effects on Soil Fertility and Nutrient Cycling in the Peruvian High‐Andean Puna Grasslands

Core Ideas A short‐term increase in fertility and greater N mineralization were found in agricultural lands. Low plant recovery and soil degradation were found in fallow soils correlated with erosion indexes. In grass‐legume mixture pastures, improved soil structure and N build up increased soil fertility. P was found as the limiting nutrient in the studied agroecosystem. Expansion of crop production into high‐altitude native grasslands is occurring in the Peruvian High‐Andes due to climate change and agricultural intensification, with little understanding of the consequences to the ecosystem. The objective of this study was to determine the impact of land‐use changes on soil fertility and nutrient cycling to guide future land management. Comparisons were made between native grasslands and two alternative farming systems; the first was a system in which native grassland was replaced by an annual cash crop, maca (Lepidium meyenii Walp.), followed by a long fallow and the second was a long‐standing perennial cultivated pasture. There was greater N mineralization, extractable Bray‐1 P, and K+ in recently converted maca soils relative to adjacent native grassland soils most likely caused by tillage‐induced nutrient mineralization and by incorporation of manure and native grassland residue during the first year of land preparation prior to planting maca. Soil fertility, as determined by an ex situ pot trial to measure plant yield, was correlated with plant cover, soil total organic carbon, and water stable aggregates (WSA) under fallow following maca, suggesting that soil erosion might be an issue in the long term. In cultivated pastures, we found an increase in long‐term fertility driven primarily by the build‐up of soil N and improved soil structure in the perennial grass‐legume mixture compared with adjacent native grassland. Responsible management of the Puna agroecosystem requires restoration of plant cover after annual cropping of maca or the establishment of mixed perennial cultivated pasture.

Influence of historical land use and modern agricultural expansion on the spatial and ecological divergence of sugarcane borer, Diatraea saccharalis (Lepidoptera: Crambidae) in Brazil.

Human-mediated changes in landscapes can facilitate niche expansion and accelerate the adaptation of insect species. The interaction between the evolutionary history of the sugarcane borer, Diatraea saccharalis Fabricius, and historical and modern agricultural activity in Brazil shaped its spatial genetic structure, facilitating ecological divergence and incipient host shifting. Based on microsatellite data, STRUCTURE analyses identified two (K = 2) and three (K = 3) significant genetic clusters that corresponded to: (a) a strong signal of spatial genetic structure and, (b) a cryptic signal of host differentiation. We inferred that K = 2 reflects the footprint of agricultural activity, such as expansion of crop production (sugarcane and maize), unintentional dispersion of pests, and management practices. In contrast, K = 3 indicated incipient host differentiation between larvae collected from sugarcane or maize. Our estimates of population size changes indicated that a historical bottleneck was associated with a reduction of sugarcane production ≈200 years ago. However, a more recent population expansion was detected (>1950s), associated with agricultural expansion of large crop production into previously unfarmed land. Partial Mantel tests supported our hypothesis of incipient host adaptation, and identified isolation-by-environment (e.g., host plant) in São Paulo and Minas Gerais states, where sugarcane has been traditionally produced in Brazil. The impact of agricultural production on D. saccharalis may continue, as the current population structure may hinder the efficacy of refuge plants in delaying insect resistance evolution to Bt toxin.

Shifting cultivation and land capability in a semiarid environment. Two examples from Botswana

Axelsen, B. 1978. Shifting cultivation and land capability in a semiarid environment. Two examples from Botswana. Norsk geogr. Tidsskr. Vol. 32, pp. 1–13. Oslo. ISSN 0029-1951. The article deals with the impact of shifting cultivation on the vegetation cover around two villages in Botswana, the first situated in the dry savanna bordering the Kalahari semidesert, the second in dry, deciduous woodland close to the Rhodesian border. The regeneration of vegetation is discussed with reference to the concept of ecological climax. Animal husbandry is important in both study areas, and widespread deterioration of ground vegetation has occurred. Future expansion of crop production and animal husbandry is discussed with reference to population and availability of land.