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Why organic resources and current fertilizer formulations in Southern Africa cannot sustain maize productivity: Evidence from a long-term experiment in Zimbabwe.

ABSTRACT: Sustainability of maize-based cropping systems is a major challenge for southern Africa, yet the demand for maize as staple food and animal feed in the region continues to increase. A study was conducted on a sandy clay loam (220 g clay kg-1 soil) at Domboshawa in Zimbabwe to investigate the long-term effects of organic resource quality and application rate, and nitrogen (N) fertilization on soil chemical properties and maize (Zea mays L.) productivity. Crotalaria juncea (high quality), Calliandra calothyrsus (medium quality), cattle manure (variable quality), maize stover and Pinus patula sawdust (both low quality) were incorporated into soil at 4.0 t C ha-1 (high rate) and 1.2 t C ha-1 (low rate) at the start of each cropping season for nine consecutive years. At both high and low application rates, each of the five organic resources was applied in combination with or without mineral nitrogen (N) fertilizer at 120 kg N ha-1. The nine-year period saw maize grain yields declining by 22% to 84% across treatments despite increases in soil organic carbon, total N and available P from 6% to 80%. Crotalaria, Calliandra and manure led to a less steep yield decline. Exchangeable calcium (Ca), magnesium (Mg) and potassium (K), and soil pH explained much of the variation in yield patterns observed under the different organic resource applications. Maize grain yield was positively correlated with exchangeable Ca (r = 0.51), Mg (r = 0.62) and K (r = 0.53), and soil pH (r = 0.49), but negatively correlated with other soil properties over the 9-year period. We concluded that declining soil exchangeable basic cations were the underlying causes of decreasing maize productivity, and was aggravated by use of low rates of organic resource inputs, particularly with N fertilization. Current nutrient management and fertilizer recommendations that emphasize inorganic N, P and K significantly undervalue the role played by organic resources in sustainability of maize cropping systems in southern Africa.

SUBMITTER: Mtangadura TJ

PROVIDER: S-EPMC5552333 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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Why organic resources and current fertilizer formulations in Southern Africa cannot sustain maize productivity: Evidence from a long-term experiment in Zimbabwe.

Mtangadura Tongai J TJ Mtambanengwe Florence F Nezomba Hatirarami H Rurinda Jairos J Mapfumo Paul P

PloS one 20170810 8

Sustainability of maize-based cropping systems is a major challenge for southern Africa, yet the demand for maize as staple food and animal feed in the region continues to increase. A study was conducted on a sandy clay loam (220 g clay kg-1 soil) at Domboshawa in Zimbabwe to investigate the long-term effects of organic resource quality and application rate, and nitrogen (N) fertilization on soil chemical properties and maize (Zea mays L.) productivity. Crotalaria juncea (high quality), Calliand ...[more]

PMID: 28797062

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Project description:Appropriate fertilizer application methods can help to improve crop yields. However, limited information is available regarding how different fertilizer application depths might affect crop production in dryland winter wheat-summer maize cropping in the Loess Plateau region of China. Therefore, we conducted field experiments in 2019–2020 and 2020–2021 to evaluate the effects of changing the fertilizer placement depth on summer maize (current crop) and winter wheat (succeeding crop) productivity, as well as the resource use efficiency and soil nitrate-nitrogen residue (SNR) level. Four fertilizer placement depths were tested comprising 5 cm (FD5), 15 cm (FD15), 25 cm (FD25), and 35 cm (FD35). The nitrogen uptake by summer maize in the two seasons was 10.0, 6.5, and 11.8% higher under FD15 compared with those under FD5, FD25, and FD35, respectively, because FD15 effectively increased the root length density, root surface area density, and rate of root bleeding sap. Due to the increased nitrogen uptake, the leaf area index, plant height, stem diameter, and accumulated dry matter were improved in summer maize. The interception of photosynthetically active radiation was 3.6, 3.7, and 5.9% higher under FD15 compared with those under FD5, FD25, and FD35, respectively. The summer maize grain yield increased by 13.9–22.4% under FD15 compared with the other treatments. In addition, the SNR in the deep soil (200–300 cm) was significantly lower under FD15 during the summer maize harvest (17.9–30.7%) compared with the other treatments. Moreover, FD15 increased the winter wheat (succeeding crop) grain yield (2.6–11.2%) and reduced the SNR in the 200–300 cm soil layer (8.8–16.8%) at the winter wheat harvest. The highest radiation use efficiency, precipitation use efficiency, and nitrogen use efficiency were obtained under FD15 in both summer maize and winter wheat. These results clearly suggest that depth fertilization of 15 cm enhanced the productivity and resource use efficiency for the current and subsequent crops in rainfed farmland in the Loess Plateau of China, as well as reducing the SNR in the deep soil to promote sustainable agricultural development. These findings provide a practical reference for optimizing fertilizer application management.

Project description:IntroductionThe aging of workers generally implies an increased number of workers with health problems or psychological diseases because of the growing distance between personal resources and job demands; the first may decrease, while the second are stable. In the preschool setting, the demands remain constant because children are always aged 0-3 years, while the preschool teacher's personal resources decrease with age. It is, therefore, necessary to propose multilevel interventions aimed at supporting work sustainability and workers' resources.MethodThis study involved twenty-seven preschools (324 teachers with an average age of 48.7 years): the control group included seventeen schools (190 teachers with an average age of 48.5 years), five schools were assigned to experimental group one (69 teachers with an average age of 48.8), and five schools were assigned to experimental group two (65 teachers with an average age of 49.1). In this context, we proposed two protocols of multilevel intervention comprising three solutions; two of these were common to both experimental groups: psychological counseling and psychosocial intervention. The third solution differed between groups: environmental redefinition (for group one); gymnastic and vocal hygiene (for group two). We hypothesized that the interventions improve teachers' work abilities, increase well-being, and decrease stress and burnout. Furthermore we hypothesized that there would be an improvement in the organizational climate of trust and in social job resources.ResultsData analysis showed that the interventions were effective. In particular, the experimental groups reported significant decreases in psychological exhaustion (EG2: ß = -1.48; p = .00), indolence (EG1: ß = -1.36; p = .00), and stress (EG2: ß = -0.94; p = .00). Furthermore, the experimental groups significantly increased their enthusiasm towards work (EG2: ß = 1.21; p = .01), vertical trust (EG1: ß = 0.54; p = .01), and the perception of coworker social support (EG2: ß = 0.54; p = .01). The protocol that involved the GC2 was particularly effective.ConclusionsThese results demonstrate the effectiveness of the intervention in a particular job setting (preschool classroom), emphasizing the need for implementing solutions aimed at supporting workers' well-being, especially in light of an aging workforce.

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Dataset Information

Why organic resources and current fertilizer formulations in Southern Africa cannot sustain maize productivity: Evidence from a long-term experiment in Zimbabwe.

Publications

Why organic resources and current fertilizer formulations in Southern Africa cannot sustain maize productivity: Evidence from a long-term experiment in Zimbabwe.

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