Simulation of Moisture Dynamics of the Soil Profile of a Maize Crop under Deficit Irrigation Scheduling

Rosana G. Moreira, Editor-in-Chief; Texas A&M UniversityThis is a paper from International Commission of Agricultural Engineering (CIGR, Commission Internationale du Genie Rural) E-Journal Volume 9 (2007): Simulation of Moisture Dynamics of the Soil Profile of a Maize Crop under Deficit Irrigation Scheduling. LW 06 015. Vol. IX. July, 2007

How much nitrogen would move down? Evaluating the effect of water application regimes on n leaching in the soil

8pNitrogen is the nutrient most often deficient for crop production and its use can result in substantial economic return to farmers. However, when N inputs exceed crop needs, excess N may contaminate water. N Management is therefore important to achieve a balance between profitable crop production and environmentally tolerable levels. The aim of this paper is to evaluate the impact of water application regimes on the leaching of nitrogen. The research study was conducted at Nkango Irrigation Scheme in Kasungu district. Maize (SC 407) planted on Julian day of 2012152 and harvested Julian day of 2012250 was used as test crop in the study. The water regimes were full (100%) water requirement regime (FWRR) of maize plant; 60% of FWRR; and 40% of FWRR. The nitrogen application regime used was 92 N kg/ha which was constant.. The EU-Rotate_N model was run to quantify nitrogen leached below 90cm of the soil profile. The study found out that water application regime has a large influence on N leaching. The study concluded that applied water in the soil should not exceed field capacity of the soil and in such way leaching of nitrogen will be minimised

Evaluation of the effectiveness of proportioning water Division Weirs in Herman Canal farmer-managed irrigation scheme, usangu plains, Tanzania

Tanzania Journal of Agricultural.Sciences. 2008 : 9 (1): 28 - 38In Tanzania, irrigated land is less than 5% of the cultivated area much of which being under traditional irrigation systems. Unfortunately, water in agriculture is indeed too often misused and mismanaged due to lack of know-how of people and weakness of institutions. This study therefore aimed at evaluating a simple approach for equitable distribution of irrigation water using proportioning water division weirs with a view to improving system performance in general. Five proportioning water division weirs were constructed along the main canal to deliver water to eight branch canals of a typical farmer-managed irrigation scheme. Flows to each of the branch canals were measured using calibrated staff gauges. The discharge data along with climatic and crop data were used in the computation of various irrigation performance indicators. Results showed productivity to be rather low, which was attributed to low-level use of inputs including sub-optimal cropping intensities. The relatively low values of output per unit irrigation supply suggest that the efficiency with which water was being used in the scheme is rather low. Overall, equity of water supply (FE = 0.14; AU = 0.52) appeared to be fair, which was an improvement over past experiences before installation of the proportioning weirs. However, in spite of improvements in water distribution, farmers still lacked basic understanding of irrigation scheduling which led to some areas being over-irrigated while others faced water shortage

Winners and losers of IWRM [Integrated Water Resources Management] in Tanzania

This paper focuses on the application of the concept of Integrated Water Resources Management (IWRM) in Tanzania. It asks: how did IWRM affect the rural and fast-growing majority of smallholder farmers' access to water which contributes directly to poverty alleviation and employment creation in a country where poverty and joblessness are high? Around 1990, there were both a strong government-led infrastructure development agenda and IWRM ingredients in place, including cost-recovery of state services aligning with the Structural Adjustment Programmes, water management according to basin boundaries and the dormant colonial water rights (permits) system. After the 1990s, the World Bank and other donors promoted IWRM with a strong focus on hydroelectric power development, River Basin Water Boards, transformation of the water right system into a taxation tool, and assessment of environmental flows. These practices became formalised in the National Water Policy (2002) and in the Water Resources Management Act (2009). Activities in the name of IWRM came to be closely associated with the post-2008 surge in large-scale land and water deals. Analysing 25 years of IWRM, the paper identifies the processes and identities of the losers (smallholders and – at least partially – the government) and the winners (large-scale water users, including recent investors). We conclude that, overall, IWRM harmed smallholders' access to water and rendered them more vulnerable to poverty and unemployment